Scoped labels (#22585)

Add a new "exclusive" option per label. This makes it so that when the
label is named `scope/name`, no other label with the same `scope/`
prefix can be set on an issue.

The scope is determined by the last occurence of `/`, so for example
`scope/alpha/name` and `scope/beta/name` are considered to be in
different scopes and can coexist.

Exclusive scopes are not enforced by any database rules, however they
are enforced when editing labels at the models level, automatically
removing any existing labels in the same scope when either attaching a
new label or replacing all labels.

In menus use a circle instead of checkbox to indicate they function as
radio buttons per scope. Issue filtering by label ensures that only a
single scoped label is selected at a time. Clicking with alt key can be
used to remove a scoped label, both when editing individual issues and
batch editing.

Label rendering refactor for consistency and code simplification:

* Labels now consistently have the same shape, emojis and tooltips
everywhere. This includes the label list and label assignment menus.
* In label list, show description below label same as label menus.
* Don't use exactly black/white text colors to look a bit nicer.
* Simplify text color computation. There is no point computing luminance
in linear color space, as this is a perceptual problem and sRGB is
closer to perceptually linear.
* Increase height of label assignment menus to show more labels. Showing
only 3-4 labels at a time leads to a lot of scrolling.
* Render all labels with a new RenderLabel template helper function.

Label creation and editing in multiline modal menu:

* Change label creation to open a modal menu like label editing.
* Change menu layout to place name, description and colors on separate
lines.
* Don't color cancel button red in label editing modal menu.
* Align text to the left in model menu for better readability and
consistent with settings layout elsewhere.

Custom exclusive scoped label rendering:

* Display scoped label prefix and suffix with slightly darker and
lighter background color respectively, and a slanted edge between them
similar to the `/` symbol.
* In menus exclusive labels are grouped with a divider line.

---------

Co-authored-by: Yarden Shoham <hrsi88@gmail.com>
Co-authored-by: Lauris BH <lauris@nix.lv>

47 files changed, 709 insertions, 242 deletions

diff --git a/models/fixtures/issue.yml b/models/fixtures/issue.yml
index 4dea8add13..174345ff5a 100644
--- a/models/fixtures/issue.yml
+++ b/models/fixtures/issue.yml
@@ -287,3 +287,20 @@
   created_unix: 1602935696
   updated_unix: 1602935696
   is_locked: false
+
+-
+  id: 18
+  repo_id: 55
+  index: 1
+  poster_id: 2
+  original_author_id: 0
+  name: issue for scoped labels
+  content: content
+  milestone_id: 0
+  priority: 0
+  is_closed: false
+  is_pull: false
+  num_comments: 0
+  created_unix: 946684830
+  updated_unix: 978307200
+  is_locked: false
diff --git a/models/fixtures/label.yml b/models/fixtures/label.yml
index 57bf804457..ab4d5ef944 100644
--- a/models/fixtures/label.yml
+++ b/models/fixtures/label.yml
@@ -4,6 +4,7 @@
   org_id: 0
   name: label1
   color: '#abcdef'
+  exclusive: false
   num_issues: 2
   num_closed_issues: 0
 
@@ -13,6 +14,7 @@
   org_id: 0
   name: label2
   color: '#000000'
+  exclusive: false
   num_issues: 1
   num_closed_issues: 1
 
@@ -22,6 +24,7 @@
   org_id: 3
   name: orglabel3
   color: '#abcdef'
+  exclusive: false
   num_issues: 0
   num_closed_issues: 0
 
@@ -31,6 +34,7 @@
   org_id: 3
   name: orglabel4
   color: '#000000'
+  exclusive: false
   num_issues: 1
   num_closed_issues: 0
 
@@ -40,5 +44,46 @@
   org_id: 0
   name: pull-test-label
   color: '#000000'
+  exclusive: false
+  num_issues: 0
+  num_closed_issues: 0
+
+-
+  id: 6
+  repo_id: 55
+  org_id: 0
+  name: unscoped_label
+  color: '#000000'
+  exclusive: false
+  num_issues: 0
+  num_closed_issues: 0
+
+-
+  id: 7
+  repo_id: 55
+  org_id: 0
+  name: scope/label1
+  color: '#000000'
+  exclusive: true
+  num_issues: 0
+  num_closed_issues: 0
+
+-
+  id: 8
+  repo_id: 55
+  org_id: 0
+  name: scope/label2
+  color: '#000000'
+  exclusive: true
+  num_issues: 0
+  num_closed_issues: 0
+
+-
+  id: 9
+  repo_id: 55
+  org_id: 0
+  name: scope/subscope/label2
+  color: '#000000'
+  exclusive: true
   num_issues: 0
   num_closed_issues: 0
diff --git a/models/fixtures/repository.yml b/models/fixtures/repository.yml
index ef3cfbbbec..58f9b919ac 100644
--- a/models/fixtures/repository.yml
+++ b/models/fixtures/repository.yml
@@ -1622,3 +1622,15 @@
   is_archived: false
   is_private: true
   status: 0
+
+-
+  id: 55
+  owner_id: 2
+  owner_name: user2
+  lower_name: scoped_label
+  name: scoped_label
+  is_empty: false
+  is_archived: false
+  is_private: true
+  num_issues: 1
+  status: 0
diff --git a/models/fixtures/user.yml b/models/fixtures/user.yml
index 63a5e0f890..0a1d85b48b 100644
--- a/models/fixtures/user.yml
+++ b/models/fixtures/user.yml
@@ -66,7 +66,7 @@
   num_followers: 2
   num_following: 1
   num_stars: 2
-  num_repos: 10
+  num_repos: 11
   num_teams: 0
   num_members: 0
   visibility: 0
diff --git a/models/issues/issue.go b/models/issues/issue.go
index b1c7fdbf7e..9d7dea0177 100644
--- a/models/issues/issue.go
+++ b/models/issues/issue.go
@@ -538,6 +538,31 @@ func (ts labelSorter) Swap(i, j int) {
 	[]*Label(ts)[i], []*Label(ts)[j] = []*Label(ts)[j], []*Label(ts)[i]
 }
 
+// Ensure only one label of a given scope exists, with labels at the end of the
+// array getting preference over earlier ones.
+func RemoveDuplicateExclusiveLabels(labels []*Label) []*Label {
+	validLabels := make([]*Label, 0, len(labels))
+
+	for i, label := range labels {
+		scope := label.ExclusiveScope()
+		if scope != "" {
+			foundOther := false
+			for _, otherLabel := range labels[i+1:] {
+				if otherLabel.ExclusiveScope() == scope {
+					foundOther = true
+					break
+				}
+			}
+			if foundOther {
+				continue
+			}
+		}
+		validLabels = append(validLabels, label)
+	}
+
+	return validLabels
+}
+
 // ReplaceIssueLabels removes all current labels and add new labels to the issue.
 // Triggers appropriate WebHooks, if any.
 func ReplaceIssueLabels(issue *Issue, labels []*Label, doer *user_model.User) (err error) {
@@ -555,6 +580,8 @@ func ReplaceIssueLabels(issue *Issue, labels []*Label, doer *user_model.User) (e
 		return err
 	}
 
+	labels = RemoveDuplicateExclusiveLabels(labels)
+
 	sort.Sort(labelSorter(labels))
 	sort.Sort(labelSorter(issue.Labels))
 
diff --git a/models/issues/issue_test.go b/models/issues/issue_test.go
index de1da19ab9..3a83d8d2b7 100644
--- a/models/issues/issue_test.go
+++ b/models/issues/issue_test.go
@@ -25,7 +25,7 @@ import (
 func TestIssue_ReplaceLabels(t *testing.T) {
 	assert.NoError(t, unittest.PrepareTestDatabase())
 
-	testSuccess := func(issueID int64, labelIDs []int64) {
+	testSuccess := func(issueID int64, labelIDs, expectedLabelIDs []int64) {
 		issue := unittest.AssertExistsAndLoadBean(t, &issues_model.Issue{ID: issueID})
 		repo := unittest.AssertExistsAndLoadBean(t, &repo_model.Repository{ID: issue.RepoID})
 		doer := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: repo.OwnerID})
@@ -35,15 +35,20 @@ func TestIssue_ReplaceLabels(t *testing.T) {
 			labels[i] = unittest.AssertExistsAndLoadBean(t, &issues_model.Label{ID: labelID, RepoID: repo.ID})
 		}
 		assert.NoError(t, issues_model.ReplaceIssueLabels(issue, labels, doer))
-		unittest.AssertCount(t, &issues_model.IssueLabel{IssueID: issueID}, len(labelIDs))
-		for _, labelID := range labelIDs {
+		unittest.AssertCount(t, &issues_model.IssueLabel{IssueID: issueID}, len(expectedLabelIDs))
+		for _, labelID := range expectedLabelIDs {
 			unittest.AssertExistsAndLoadBean(t, &issues_model.IssueLabel{IssueID: issueID, LabelID: labelID})
 		}
 	}
 
-	testSuccess(1, []int64{2})
-	testSuccess(1, []int64{1, 2})
-	testSuccess(1, []int64{})
+	testSuccess(1, []int64{2}, []int64{2})
+	testSuccess(1, []int64{1, 2}, []int64{1, 2})
+	testSuccess(1, []int64{}, []int64{})
+
+	// mutually exclusive scoped labels 7 and 8
+	testSuccess(18, []int64{6, 7}, []int64{6, 7})
+	testSuccess(18, []int64{7, 8}, []int64{8})
+	testSuccess(18, []int64{6, 8, 7}, []int64{6, 7})
 }
 
 func Test_GetIssueIDsByRepoID(t *testing.T) {
@@ -523,5 +528,5 @@ func TestCountIssues(t *testing.T) {
 	assert.NoError(t, unittest.PrepareTestDatabase())
 	count, err := issues_model.CountIssues(db.DefaultContext, &issues_model.IssuesOptions{})
 	assert.NoError(t, err)
-	assert.EqualValues(t, 17, count)
+	assert.EqualValues(t, 18, count)
 }
diff --git a/models/issues/label.go b/models/issues/label.go
index dbb7a139ef..0dd12fb5c9 100644
--- a/models/issues/label.go
+++ b/models/issues/label.go
@@ -7,8 +7,6 @@ package issues
 import (
 	"context"
 	"fmt"
-	"html/template"
-	"math"
 	"regexp"
 	"strconv"
 	"strings"
@@ -89,6 +87,7 @@ type Label struct {
 	RepoID          int64 `xorm:"INDEX"`
 	OrgID           int64 `xorm:"INDEX"`
 	Name            string
+	Exclusive       bool
 	Description     string
 	Color           string `xorm:"VARCHAR(7)"`
 	NumIssues       int
@@ -128,18 +127,22 @@ func (label *Label) CalOpenOrgIssues(ctx context.Context, repoID, labelID int64)
 }
 
 // LoadSelectedLabelsAfterClick calculates the set of selected labels when a label is clicked
-func (label *Label) LoadSelectedLabelsAfterClick(currentSelectedLabels []int64) {
+func (label *Label) LoadSelectedLabelsAfterClick(currentSelectedLabels []int64, currentSelectedExclusiveScopes []string) {
 	var labelQuerySlice []string
 	labelSelected := false
 	labelID := strconv.FormatInt(label.ID, 10)
-	for _, s := range currentSelectedLabels {
+	labelScope := label.ExclusiveScope()
+	for i, s := range currentSelectedLabels {
 		if s == label.ID {
 			labelSelected = true
 		} else if -s == label.ID {
 			labelSelected = true
 			label.IsExcluded = true
 		} else if s != 0 {
-			labelQuerySlice = append(labelQuerySlice, strconv.FormatInt(s, 10))
+			// Exclude other labels in the same scope from selection
+			if s < 0 || labelScope == "" || labelScope != currentSelectedExclusiveScopes[i] {
+				labelQuerySlice = append(labelQuerySlice, strconv.FormatInt(s, 10))
+			}
 		}
 	}
 	if !labelSelected {
@@ -159,49 +162,43 @@ func (label *Label) BelongsToRepo() bool {
 	return label.RepoID > 0
 }
 
-// SrgbToLinear converts a component of an sRGB color to its linear intensity
-// See: https://en.wikipedia.org/wiki/SRGB#The_reverse_transformation_(sRGB_to_CIE_XYZ)
-func SrgbToLinear(color uint8) float64 {
-	flt := float64(color) / 255
-	if flt <= 0.04045 {
-		return flt / 12.92
+// Get color as RGB values in 0..255 range
+func (label *Label) ColorRGB() (float64, float64, float64, error) {
+	color, err := strconv.ParseUint(label.Color[1:], 16, 64)
+	if err != nil {
+		return 0, 0, 0, err
 	}
-	return math.Pow((flt+0.055)/1.055, 2.4)
-}
-
-// Luminance returns the luminance of an sRGB color
-func Luminance(color uint32) float64 {
-	r := SrgbToLinear(uint8(0xFF & (color >> 16)))
-	g := SrgbToLinear(uint8(0xFF & (color >> 8)))
-	b := SrgbToLinear(uint8(0xFF & color))
 
-	// luminance ratios for sRGB
-	return 0.2126*r + 0.7152*g + 0.0722*b
+	r := float64(uint8(0xFF & (uint32(color) >> 16)))
+	g := float64(uint8(0xFF & (uint32(color) >> 8)))
+	b := float64(uint8(0xFF & uint32(color)))
+	return r, g, b, nil
 }
 
-// LuminanceThreshold is the luminance at which white and black appear to have the same contrast
-// i.e. x such that 1.05 / (x + 0.05) = (x + 0.05) / 0.05
-// i.e. math.Sqrt(1.05*0.05) - 0.05
-const LuminanceThreshold float64 = 0.179
-
-// ForegroundColor calculates the text color for labels based
-// on their background color.
-func (label *Label) ForegroundColor() template.CSS {
+// Determine if label text should be light or dark to be readable on background color
+func (label *Label) UseLightTextColor() bool {
 	if strings.HasPrefix(label.Color, "#") {
-		if color, err := strconv.ParseUint(label.Color[1:], 16, 64); err == nil {
-			// NOTE: see web_src/js/components/ContextPopup.vue for similar implementation
-			luminance := Luminance(uint32(color))
-
-			// prefer white or black based upon contrast
-			if luminance < LuminanceThreshold {
-				return template.CSS("#fff")
-			}
-			return template.CSS("#000")
+		if r, g, b, err := label.ColorRGB(); err == nil {
+			// Perceived brightness from: https://www.w3.org/TR/AERT/#color-contrast
+			// In the future WCAG 3 APCA may be a better solution
+			brightness := (0.299*r + 0.587*g + 0.114*b) / 255
+			return brightness < 0.35
 		}
 	}
 
-	// default to black
-	return template.CSS("#000")
+	return false
+}
+
+// Return scope substring of label name, or empty string if none exists
+func (label *Label) ExclusiveScope() string {
+	if !label.Exclusive {
+		return ""
+	}
+	lastIndex := strings.LastIndex(label.Name, "/")
+	if lastIndex == -1 || lastIndex == 0 || lastIndex == len(label.Name)-1 {
+		return ""
+	}
+	return label.Name[:lastIndex]
 }
 
 // NewLabel creates a new label
@@ -253,7 +250,7 @@ func UpdateLabel(l *Label) error {
 	if !LabelColorPattern.MatchString(l.Color) {
 		return fmt.Errorf("bad color code: %s", l.Color)
 	}
-	return updateLabelCols(db.DefaultContext, l, "name", "description", "color")
+	return updateLabelCols(db.DefaultContext, l, "name", "description", "color", "exclusive")
 }
 
 // DeleteLabel delete a label
@@ -620,6 +617,29 @@ func newIssueLabel(ctx context.Context, issue *Issue, label *Label, doer *user_m
 	return updateLabelCols(ctx, label, "num_issues", "num_closed_issue")
 }
 
+// Remove all issue labels in the given exclusive scope
+func RemoveDuplicateExclusiveIssueLabels(ctx context.Context, issue *Issue, label *Label, doer *user_model.User) (err error) {
+	scope := label.ExclusiveScope()
+	if scope == "" {
+		return nil
+	}
+
+	var toRemove []*Label
+	for _, issueLabel := range issue.Labels {
+		if label.ID != issueLabel.ID && issueLabel.ExclusiveScope() == scope {
+			toRemove = append(toRemove, issueLabel)
+		}
+	}
+
+	for _, issueLabel := range toRemove {
+		if err = deleteIssueLabel(ctx, issue, issueLabel, doer); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
 // NewIssueLabel creates a new issue-label relation.
 func NewIssueLabel(issue *Issue, label *Label, doer *user_model.User) (err error) {
 	if HasIssueLabel(db.DefaultContext, issue.ID, label.ID) {
@@ -641,6 +661,10 @@ func NewIssueLabel(issue *Issue, label *Label, doer *user_model.User) (err error
 		return nil
 	}
 
+	if err = RemoveDuplicateExclusiveIssueLabels(ctx, issue, label, doer); err != nil {
+		return nil
+	}
+
 	if err = newIssueLabel(ctx, issue, label, doer); err != nil {
 		return err
 	}
diff --git a/models/issues/label_test.go b/models/issues/label_test.go
index 239e328d47..0e45e0db0b 100644
--- a/models/issues/label_test.go
+++ b/models/issues/label_test.go
@@ -4,7 +4,6 @@
 package issues_test
 
 import (
-	"html/template"
 	"testing"
 
 	"code.gitea.io/gitea/models/db"
@@ -25,13 +24,22 @@ func TestLabel_CalOpenIssues(t *testing.T) {
 	assert.EqualValues(t, 2, label.NumOpenIssues)
 }
 
-func TestLabel_ForegroundColor(t *testing.T) {
+func TestLabel_TextColor(t *testing.T) {
 	assert.NoError(t, unittest.PrepareTestDatabase())
 	label := unittest.AssertExistsAndLoadBean(t, &issues_model.Label{ID: 1})
-	assert.Equal(t, template.CSS("#000"), label.ForegroundColor())
+	assert.False(t, label.UseLightTextColor())
 
 	label = unittest.AssertExistsAndLoadBean(t, &issues_model.Label{ID: 2})
-	assert.Equal(t, template.CSS("#fff"), label.ForegroundColor())
+	assert.True(t, label.UseLightTextColor())
+}
+
+func TestLabel_ExclusiveScope(t *testing.T) {
+	assert.NoError(t, unittest.PrepareTestDatabase())
+	label := unittest.AssertExistsAndLoadBean(t, &issues_model.Label{ID: 7})
+	assert.Equal(t, "scope", label.ExclusiveScope())
+
+	label = unittest.AssertExistsAndLoadBean(t, &issues_model.Label{ID: 9})
+	assert.Equal(t, "scope/subscope", label.ExclusiveScope())
 }
 
 func TestNewLabels(t *testing.T) {
@@ -266,6 +274,7 @@ func TestUpdateLabel(t *testing.T) {
 		Color:       "#ffff00",
 		Name:        "newLabelName",
 		Description: label.Description,
+		Exclusive:   false,
 	}
 	label.Color = update.Color
 	label.Name = update.Name
@@ -323,6 +332,34 @@ func TestNewIssueLabel(t *testing.T) {
 	unittest.CheckConsistencyFor(t, &issues_model.Issue{}, &issues_model.Label{})
 }
 
+func TestNewIssueExclusiveLabel(t *testing.T) {
+	assert.NoError(t, unittest.PrepareTestDatabase())
+	issue := unittest.AssertExistsAndLoadBean(t, &issues_model.Issue{ID: 18})
+	doer := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 2})
+
+	otherLabel := unittest.AssertExistsAndLoadBean(t, &issues_model.Label{ID: 6})
+	exclusiveLabelA := unittest.AssertExistsAndLoadBean(t, &issues_model.Label{ID: 7})
+	exclusiveLabelB := unittest.AssertExistsAndLoadBean(t, &issues_model.Label{ID: 8})
+
+	// coexisting regular and exclusive label
+	assert.NoError(t, issues_model.NewIssueLabel(issue, otherLabel, doer))
+	assert.NoError(t, issues_model.NewIssueLabel(issue, exclusiveLabelA, doer))
+	unittest.AssertExistsAndLoadBean(t, &issues_model.IssueLabel{IssueID: issue.ID, LabelID: otherLabel.ID})
+	unittest.AssertExistsAndLoadBean(t, &issues_model.IssueLabel{IssueID: issue.ID, LabelID: exclusiveLabelA.ID})
+
+	// exclusive label replaces existing one
+	assert.NoError(t, issues_model.NewIssueLabel(issue, exclusiveLabelB, doer))
+	unittest.AssertExistsAndLoadBean(t, &issues_model.IssueLabel{IssueID: issue.ID, LabelID: otherLabel.ID})
+	unittest.AssertExistsAndLoadBean(t, &issues_model.IssueLabel{IssueID: issue.ID, LabelID: exclusiveLabelB.ID})
+	unittest.AssertNotExistsBean(t, &issues_model.IssueLabel{IssueID: issue.ID, LabelID: exclusiveLabelA.ID})
+
+	// exclusive label replaces existing one again
+	assert.NoError(t, issues_model.NewIssueLabel(issue, exclusiveLabelA, doer))
+	unittest.AssertExistsAndLoadBean(t, &issues_model.IssueLabel{IssueID: issue.ID, LabelID: otherLabel.ID})
+	unittest.AssertExistsAndLoadBean(t, &issues_model.IssueLabel{IssueID: issue.ID, LabelID: exclusiveLabelA.ID})
+	unittest.AssertNotExistsBean(t, &issues_model.IssueLabel{IssueID: issue.ID, LabelID: exclusiveLabelB.ID})
+}
+
 func TestNewIssueLabels(t *testing.T) {
 	assert.NoError(t, unittest.PrepareTestDatabase())
 	label1 := unittest.AssertExistsAndLoadBean(t, &issues_model.Label{ID: 1})
diff --git a/models/migrations/fixtures/Test_DeleteOrphanedIssueLabels/label.yml b/models/migrations/fixtures/Test_DeleteOrphanedIssueLabels/label.yml
index d651c87d5b..085b7f0882 100644
--- a/models/migrations/fixtures/Test_DeleteOrphanedIssueLabels/label.yml
+++ b/models/migrations/fixtures/Test_DeleteOrphanedIssueLabels/label.yml
@@ -4,6 +4,7 @@
   org_id: 0
   name: label1
   color: '#abcdef'
+  exclusive: false
   num_issues: 2
   num_closed_issues: 0
 
@@ -13,6 +14,7 @@
   org_id: 0
   name: label2
   color: '#000000'
+  exclusive: false
   num_issues: 1
   num_closed_issues: 1
 -
@@ -21,6 +23,7 @@
   org_id:  3
   name: orglabel3
   color: '#abcdef'
+  exclusive: false
   num_issues: 0
   num_closed_issues: 0
 
@@ -30,6 +33,7 @@
   org_id: 3
   name: orglabel4
   color: '#000000'
+  exclusive: false
   num_issues: 1
   num_closed_issues: 0
 
@@ -39,5 +43,6 @@
   org_id: 0
   name: pull-test-label
   color: '#000000'
+  exclusive: false
   num_issues: 0
   num_closed_issues: 0
diff --git a/models/migrations/migrations.go b/models/migrations/migrations.go
index 73c44f008a..c7497becd1 100644
--- a/models/migrations/migrations.go
+++ b/models/migrations/migrations.go
@@ -459,6 +459,8 @@ var migrations = []Migration{
 	NewMigration("Add card_type column to project table", v1_19.AddCardTypeToProjectTable),
 	// v242 -> v243
 	NewMigration("Alter gpg_key_import content TEXT field to MEDIUMTEXT", v1_19.AlterPublicGPGKeyImportContentFieldToMediumText),
+	// v243 -> v244
+	NewMigration("Add exclusive label", v1_19.AddExclusiveLabel),
 }
 
 // GetCurrentDBVersion returns the current db version
diff --git a/models/migrations/v1_19/v244.go b/models/migrations/v1_19/v244.go
new file mode 100644
index 0000000000..55bbfafb2f
--- /dev/null
+++ b/models/migrations/v1_19/v244.go
@@ -0,0 +1,16 @@
+// Copyright 2023 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package v1_19 //nolint
+
+import (
+	"xorm.io/xorm"
+)
+
+func AddExclusiveLabel(x *xorm.Engine) error {
+	type Label struct {
+		Exclusive bool
+	}
+
+	return x.Sync(new(Label))
+}
diff --git a/modules/migration/label.go b/modules/migration/label.go
index 38f0eb10da..4927be3c0b 100644
--- a/modules/migration/label.go
+++ b/modules/migration/label.go
@@ -9,4 +9,5 @@ type Label struct {
 	Name        string `json:"name"`
 	Color       string `json:"color"`
 	Description string `json:"description"`
+	Exclusive   bool   `json:"exclusive"`
 }
diff --git a/modules/structs/issue_label.go b/modules/structs/issue_label.go
index 5c622797f4..5bb6cc3b84 100644
--- a/modules/structs/issue_label.go
+++ b/modules/structs/issue_label.go
@@ -9,6 +9,8 @@ package structs
 type Label struct {
 	ID   int64  `json:"id"`
 	Name string `json:"name"`
+	// example: false
+	Exclusive bool `json:"exclusive"`
 	// example: 00aabb
 	Color       string `json:"color"`
 	Description string `json:"description"`
@@ -19,6 +21,8 @@ type Label struct {
 type CreateLabelOption struct {
 	// required:true
 	Name string `json:"name" binding:"Required"`
+	// example: false
+	Exclusive bool `json:"exclusive"`
 	// required:true
 	// example: #00aabb
 	Color       string `json:"color" binding:"Required"`
@@ -27,7 +31,10 @@ type CreateLabelOption struct {
 
 // EditLabelOption options for editing a label
 type EditLabelOption struct {
-	Name        *string `json:"name"`
+	Name *string `json:"name"`
+	// example: false
+	Exclusive *bool `json:"exclusive"`
+	// example: #00aabb
 	Color       *string `json:"color"`
 	Description *string `json:"description"`
 }
diff --git a/modules/templates/helper.go b/modules/templates/helper.go
index 8f8f565c1f..4ffd0a5dee 100644
--- a/modules/templates/helper.go
+++ b/modules/templates/helper.go
@@ -7,10 +7,12 @@ package templates
 import (
 	"bytes"
 	"context"
+	"encoding/hex"
 	"errors"
 	"fmt"
 	"html"
 	"html/template"
+	"math"
 	"mime"
 	"net/url"
 	"path/filepath"
@@ -382,6 +384,9 @@ func NewFuncMap() []template.FuncMap {
 			// the table is NOT sorted with this header
 			return ""
 		},
+		"RenderLabel": func(label *issues_model.Label) template.HTML {
+			return template.HTML(RenderLabel(label))
+		},
 		"RenderLabels": func(labels []*issues_model.Label, repoLink string) template.HTML {
 			htmlCode := `<span class="labels-list">`
 			for _, label := range labels {
@@ -389,8 +394,8 @@ func NewFuncMap() []template.FuncMap {
 				if label == nil {
 					continue
 				}
-				htmlCode += fmt.Sprintf("<a href='%s/issues?labels=%d' class='ui label' style='color: %s !important; background-color: %s !important' title='%s'>%s</a> ",
-					repoLink, label.ID, label.ForegroundColor(), label.Color, html.EscapeString(label.Description), RenderEmoji(label.Name))
+				htmlCode += fmt.Sprintf("<a href='%s/issues?labels=%d'>%s</a> ",
+					repoLink, label.ID, RenderLabel(label))
 			}
 			htmlCode += "</span>"
 			return template.HTML(htmlCode)
@@ -801,6 +806,67 @@ func RenderIssueTitle(ctx context.Context, text, urlPrefix string, metas map[str
 	return template.HTML(renderedText)
 }
 
+// RenderLabel renders a label
+func RenderLabel(label *issues_model.Label) string {
+	labelScope := label.ExclusiveScope()
+
+	textColor := "#111"
+	if label.UseLightTextColor() {
+		textColor = "#eee"
+	}
+
+	description := emoji.ReplaceAliases(template.HTMLEscapeString(label.Description))
+
+	if labelScope == "" {
+		// Regular label
+		return fmt.Sprintf("<div class='ui label' style='color: %s !important; background-color: %s !important' title='%s'>%s</div>",
+			textColor, label.Color, description, RenderEmoji(label.Name))
+	}
+
+	// Scoped label
+	scopeText := RenderEmoji(labelScope)
+	itemText := RenderEmoji(label.Name[len(labelScope)+1:])
+
+	itemColor := label.Color
+	scopeColor := label.Color
+	if r, g, b, err := label.ColorRGB(); err == nil {
+		// Make scope and item background colors slightly darker and lighter respectively.
+		// More contrast needed with higher luminance, empirically tweaked.
+		luminance := (0.299*r + 0.587*g + 0.114*b) / 255
+		contrast := 0.01 + luminance*0.06
+		// Ensure we add the same amount of contrast also near 0 and 1.
+		darken := contrast + math.Max(luminance+contrast-1.0, 0.0)
+		lighten := contrast + math.Max(contrast-luminance, 0.0)
+		// Compute factor to keep RGB values proportional.
+		darkenFactor := math.Max(luminance-darken, 0.0) / math.Max(luminance, 1.0/255.0)
+		lightenFactor := math.Min(luminance+lighten, 1.0) / math.Max(luminance, 1.0/255.0)
+
+		scopeBytes := []byte{
+			uint8(math.Min(math.Round(r*darkenFactor), 255)),
+			uint8(math.Min(math.Round(g*darkenFactor), 255)),
+			uint8(math.Min(math.Round(b*darkenFactor), 255)),
+		}
+		itemBytes := []byte{
+			uint8(math.Min(math.Round(r*lightenFactor), 255)),
+			uint8(math.Min(math.Round(g*lightenFactor), 255)),
+			uint8(math.Min(math.Round(b*lightenFactor), 255)),
+		}
+
+		itemColor = "#" + hex.EncodeToString(itemBytes)
+		scopeColor = "#" + hex.EncodeToString(scopeBytes)
+	}
+
+	return fmt.Sprintf("<span class='ui label scope-parent' title='%s'>"+
+		"<div class='ui label scope-left' style='color: %s !important; background-color: %s !important'>%s</div>"+
+		"<div class='ui label scope-middle' style='background: linear-gradient(-80deg, %s 48%%, %s 52%% 0%%);'>&nbsp;</div>"+
+		"<div class='ui label scope-right' style='color: %s !important; background-color: %s !important''>%s</div>"+
+		"</span>",
+		description,
+		textColor, scopeColor, scopeText,
+		itemColor, scopeColor,
+		textColor, itemColor, itemText)
+}
+
 // RenderEmoji renders html text with emoji post processors
 func RenderEmoji(text string) template.HTML {
 	renderedText, err := markup.RenderEmoji(template.HTMLEscapeString(text))
diff --git a/options/locale/locale_en-US.ini b/options/locale/locale_en-US.ini
index 51ae8c7a02..411a585c81 100644
--- a/options/locale/locale_en-US.ini
+++ b/options/locale/locale_en-US.ini
@@ -1395,9 +1395,12 @@ issues.sign_in_require_desc = <a href="%s">Sign in</a> to join this conversation
 issues.edit = Edit
 issues.cancel = Cancel
 issues.save = Save
-issues.label_title = Label name
-issues.label_description = Label description
-issues.label_color = Label color
+issues.label_title = Name
+issues.label_description = Description
+issues.label_color = Color
+issues.label_exclusive = Exclusive
+issues.label_exclusive_desc = Name the label <code>scope/item</code> to make it mutually exclusive with other <code>scope/</code> labels.
+issues.label_exclusive_warning = Any conflicting scoped labels will be removed when editing the labels of an issue or pull request.
 issues.label_count = %d labels
 issues.label_open_issues = %d open issues/pull requests
 issues.label_edit = Edit
diff --git a/routers/api/v1/org/label.go b/routers/api/v1/org/label.go
index 5d0455cdd4..938fe79df6 100644
--- a/routers/api/v1/org/label.go
+++ b/routers/api/v1/org/label.go
@@ -94,6 +94,7 @@ func CreateLabel(ctx *context.APIContext) {
 
 	label := &issues_model.Label{
 		Name:        form.Name,
+		Exclusive:   form.Exclusive,
 		Color:       form.Color,
 		OrgID:       ctx.Org.Organization.ID,
 		Description: form.Description,
@@ -195,6 +196,9 @@ func EditLabel(ctx *context.APIContext) {
 	if form.Name != nil {
 		label.Name = *form.Name
 	}
+	if form.Exclusive != nil {
+		label.Exclusive = *form.Exclusive
+	}
 	if form.Color != nil {
 		label.Color = strings.Trim(*form.Color, " ")
 		if len(label.Color) == 6 {
diff --git a/routers/api/v1/repo/label.go b/routers/api/v1/repo/label.go
index 411c0274e6..a06d26e837 100644
--- a/routers/api/v1/repo/label.go
+++ b/routers/api/v1/repo/label.go
@@ -156,6 +156,7 @@ func CreateLabel(ctx *context.APIContext) {
 
 	label := &issues_model.Label{
 		Name:        form.Name,
+		Exclusive:   form.Exclusive,
 		Color:       form.Color,
 		RepoID:      ctx.Repo.Repository.ID,
 		Description: form.Description,
@@ -218,6 +219,9 @@ func EditLabel(ctx *context.APIContext) {
 	if form.Name != nil {
 		label.Name = *form.Name
 	}
+	if form.Exclusive != nil {
+		label.Exclusive = *form.Exclusive
+	}
 	if form.Color != nil {
 		label.Color = strings.Trim(*form.Color, " ")
 		if len(label.Color) == 6 {
diff --git a/routers/web/org/org_labels.go b/routers/web/org/org_labels.go
index 1c910a93a5..e96627762b 100644
--- a/routers/web/org/org_labels.go
+++ b/routers/web/org/org_labels.go
@@ -45,6 +45,7 @@ func NewLabel(ctx *context.Context) {
 	l := &issues_model.Label{
 		OrgID:       ctx.Org.Organization.ID,
 		Name:        form.Title,
+		Exclusive:   form.Exclusive,
 		Description: form.Description,
 		Color:       form.Color,
 	}
@@ -70,6 +71,7 @@ func UpdateLabel(ctx *context.Context) {
 	}
 
 	l.Name = form.Title
+	l.Exclusive = form.Exclusive
 	l.Description = form.Description
 	l.Color = form.Color
 	if err := issues_model.UpdateLabel(l); err != nil {
diff --git a/routers/web/repo/issue.go b/routers/web/repo/issue.go
index 62565af50f..05ba26a70c 100644
--- a/routers/web/repo/issue.go
+++ b/routers/web/repo/issue.go
@@ -332,8 +332,24 @@ func issues(ctx *context.Context, milestoneID, projectID int64, isPullOption uti
 		labels = append(labels, orgLabels...)
 	}
 
+	// Get the exclusive scope for every label ID
+	labelExclusiveScopes := make([]string, 0, len(labelIDs))
+	for _, labelID := range labelIDs {
+		foundExclusiveScope := false
+		for _, label := range labels {
+			if label.ID == labelID || label.ID == -labelID {
+				labelExclusiveScopes = append(labelExclusiveScopes, label.ExclusiveScope())
+				foundExclusiveScope = true
+				break
+			}
+		}
+		if !foundExclusiveScope {
+			labelExclusiveScopes = append(labelExclusiveScopes, "")
+		}
+	}
+
 	for _, l := range labels {
-		l.LoadSelectedLabelsAfterClick(labelIDs)
+		l.LoadSelectedLabelsAfterClick(labelIDs, labelExclusiveScopes)
 	}
 	ctx.Data["Labels"] = labels
 	ctx.Data["NumLabels"] = len(labels)
diff --git a/routers/web/repo/issue_label.go b/routers/web/repo/issue_label.go
index 66e8920bd9..d4fece9f01 100644
--- a/routers/web/repo/issue_label.go
+++ b/routers/web/repo/issue_label.go
@@ -113,6 +113,7 @@ func NewLabel(ctx *context.Context) {
 	l := &issues_model.Label{
 		RepoID:      ctx.Repo.Repository.ID,
 		Name:        form.Title,
+		Exclusive:   form.Exclusive,
 		Description: form.Description,
 		Color:       form.Color,
 	}
@@ -138,6 +139,7 @@ func UpdateLabel(ctx *context.Context) {
 	}
 
 	l.Name = form.Title
+	l.Exclusive = form.Exclusive
 	l.Description = form.Description
 	l.Color = form.Color
 	if err := issues_model.UpdateLabel(l); err != nil {
@@ -175,7 +177,7 @@ func UpdateIssueLabel(ctx *context.Context) {
 				return
 			}
 		}
-	case "attach", "detach", "toggle":
+	case "attach", "detach", "toggle", "toggle-alt":
 		label, err := issues_model.GetLabelByID(ctx, ctx.FormInt64("id"))
 		if err != nil {
 			if issues_model.IsErrRepoLabelNotExist(err) {
@@ -189,12 +191,18 @@ func UpdateIssueLabel(ctx *context.Context) {
 		if action == "toggle" {
 			// detach if any issues already have label, otherwise attach
 			action = "attach"
-			for _, issue := range issues {
-				if issues_model.HasIssueLabel(ctx, issue.ID, label.ID) {
-					action = "detach"
-					break
+			if label.ExclusiveScope() == "" {
+				for _, issue := range issues {
+					if issues_model.HasIssueLabel(ctx, issue.ID, label.ID) {
+						action = "detach"
+						break
+					}
 				}
 			}
+		} else if action == "toggle-alt" {
+			// always detach with alt key pressed, to be able to remove
+			// scoped labels
+			action = "detach"
 		}
 
 		if action == "attach" {
diff --git a/services/convert/issue.go b/services/convert/issue.go
index dccf2f3727..e79fcfcccb 100644
--- a/services/convert/issue.go
+++ b/services/convert/issue.go
@@ -182,6 +182,7 @@ func ToLabel(label *issues_model.Label, repo *repo_model.Repository, org *user_m
 	result := &api.Label{
 		ID:          label.ID,
 		Name:        label.Name,
+		Exclusive:   label.Exclusive,
 		Color:       strings.TrimLeft(label.Color, "#"),
 		Description: label.Description,
 	}
diff --git a/services/forms/repo_form.go b/services/forms/repo_form.go
index c1b5800968..ff0916f8e1 100644
--- a/services/forms/repo_form.go
+++ b/services/forms/repo_form.go
@@ -564,6 +564,7 @@ func (f *CreateMilestoneForm) Validate(req *http.Request, errs binding.Errors) b
 type CreateLabelForm struct {
 	ID          int64
 	Title       string `binding:"Required;MaxSize(50)" locale:"repo.issues.label_title"`
+	Exclusive   bool   `form:"exclusive"`
 	Description string `binding:"MaxSize(200)" locale:"repo.issues.label_description"`
 	Color       string `binding:"Required;MaxSize(7)" locale:"repo.issues.label_color"`
 }
diff --git a/services/migrations/main_test.go b/services/migrations/main_test.go
index 30875f6e5b..42c433fb00 100644
--- a/services/migrations/main_test.go
+++ b/services/migrations/main_test.go
@@ -59,6 +59,7 @@ func assertCommentsEqual(t *testing.T, expected, actual []*base.Comment) {
 
 func assertLabelEqual(t *testing.T, expected, actual *base.Label) {
 	assert.Equal(t, expected.Name, actual.Name)
+	assert.Equal(t, expected.Exclusive, actual.Exclusive)
 	assert.Equal(t, expected.Color, actual.Color)
 	assert.Equal(t, expected.Description, actual.Description)
 }
diff --git a/services/repository/template.go b/services/repository/template.go
index 13e0749869..8c75948c41 100644
--- a/services/repository/template.go
+++ b/services/repository/template.go
@@ -31,6 +31,7 @@ func GenerateIssueLabels(ctx context.Context, templateRepo, generateRepo *repo_m
 		newLabels = append(newLabels, &issues_model.Label{
 			RepoID:      generateRepo.ID,
 			Name:        templateLabel.Name,
+			Exclusive:   templateLabel.Exclusive,
 			Description: templateLabel.Description,
 			Color:       templateLabel.Color,
 		})
diff --git a/templates/projects/view.tmpl b/templates/projects/view.tmpl
index 112e6be7ce..b25cf2526e 100644
--- a/templates/projects/view.tmpl
+++ b/templates/projects/view.tmpl
@@ -234,7 +234,7 @@
 						{{if or .Labels .Assignees}}
 						<div class="extra content labels-list gt-p-0 gt-pt-2">
 							{{range .Labels}}
-								<a class="ui label" target="_blank" href="{{$.RepoLink}}/issues?labels={{.ID}}" style="color: {{.ForegroundColor}}; background-color: {{.Color}};" title="{{.Description | RenderEmojiPlain}}">{{.Name | RenderEmoji}}</a>
+								<a target="_blank" href="{{$.RepoLink}}/issues?labels={{.ID}}">{{RenderLabel .}}</a>
 							{{end}}
 							<div class="right floated">
 								{{range .Assignees}}
diff --git a/templates/repo/issue/labels/edit_delete_label.tmpl b/templates/repo/issue/labels/edit_delete_label.tmpl
index a0479dde1b..450061e835 100644
--- a/templates/repo/issue/labels/edit_delete_label.tmpl
+++ b/templates/repo/issue/labels/edit_delete_label.tmpl
@@ -26,31 +26,45 @@
 		<form class="ui edit-label form ignore-dirty" action="{{$.Link}}/edit" method="post">
 			{{.CsrfTokenHtml}}
 			<input id="label-modal-id" name="id" type="hidden">
-			<div class="ui grid">
-				<div class="three wide column">
-					<div class="ui small input">
-						<input class="new-label-input emoji-input" name="title" placeholder="{{.locale.Tr "repo.issues.new_label_placeholder"}}" autofocus required maxlength="50">
-					</div>
+			<div class="required field">
+				<label for="name">{{.locale.Tr "repo.issues.label_title"}}</label>
+				<div class="ui small input">
+					<input class="label-name-input emoji-input" name="title" placeholder="{{.locale.Tr "repo.issues.new_label_placeholder"}}" autofocus required maxlength="50">
 				</div>
-				<div class="five wide column">
-					<div class="ui small fluid input">
-						<input class="new-label-desc-input" name="description" placeholder="{{.locale.Tr "repo.issues.new_label_desc_placeholder"}}" maxlength="200">
-					</div>
+			</div>
+			<div class="field label-exclusive-input-field">
+				<div class="ui checkbox">
+					<input class="label-exclusive-input" name="exclusive" type="checkbox">
+					<label>{{.locale.Tr "repo.issues.label_exclusive"}}</label>
 				</div>
+				<br/>
+				<small class="desc">{{.locale.Tr "repo.issues.label_exclusive_desc" | Safe}}</small>
+				<div class="desc gt-ml-2 gt-mt-3 gt-hidden label-exclusive-warning">
+					{{svg "octicon-alert"}} {{.locale.Tr "repo.issues.label_exclusive_warning" | Safe}}
+				</div>
+			</div>
+			<div class="field">
+				<label for="description">{{.locale.Tr "repo.issues.label_description"}}</label>
+				<div class="ui small fluid input">
+					<input class="label-desc-input" name="description" placeholder="{{.locale.Tr "repo.issues.new_label_desc_placeholder"}}" maxlength="200">
+				</div>
+			</div>
+			<div class="field color-field">
+				<label for="color">{{$.locale.Tr "repo.issues.label_color"}}</label>
 				<div class="color picker column">
 					<input class="color-picker" name="color" value="#70c24a" required maxlength="7">
-				</div>
-				<div class="column precolors">
-					{{template "repo/issue/label_precolors"}}
+					<div class="column precolors">
+						{{template "repo/issue/label_precolors"}}
+					</div>
 				</div>
 			</div>
 		</form>
 	</div>
 	<div class="actions">
-		<div class="ui negative button">
+		<div class="ui secondary small basic cancel button">
 			{{.locale.Tr "cancel"}}
 		</div>
-		<div class="ui positive button">
+		<div class="ui primary small approve button">
 			{{.locale.Tr "save"}}
 		</div>
 	</div>
diff --git a/templates/repo/issue/labels/label.tmpl b/templates/repo/issue/labels/label.tmpl
index 0afe5cb6e7..87d8f0c41c 100644
--- a/templates/repo/issue/labels/label.tmpl
+++ b/templates/repo/issue/labels/label.tmpl
@@ -1,9 +1,7 @@
 <a
-	class="ui label item {{if not .label.IsChecked}}hide{{end}}"
+	class="item {{if not .label.IsChecked}}hide{{end}}"
 	id="label_{{.label.ID}}"
 	href="{{.root.RepoLink}}/{{if or .root.IsPull .root.Issue.IsPull}}pulls{{else}}issues{{end}}?labels={{.label.ID}}"{{/* FIXME: use .root.Issue.Link or create .root.Link */}}
-	style="color: {{.label.ForegroundColor}}; background-color: {{.label.Color}}"
-	title="{{.label.Description | RenderEmojiPlain}}"
 >
-	{{.label.Name | RenderEmoji}}
+	{{RenderLabel .label}}
 </a>
diff --git a/templates/repo/issue/labels/label_list.tmpl b/templates/repo/issue/labels/label_list.tmpl
index 464c9fe208..e8f00fa256 100644
--- a/templates/repo/issue/labels/label_list.tmpl
+++ b/templates/repo/issue/labels/label_list.tmpl
@@ -30,28 +30,24 @@
 		{{range .Labels}}
 			<li class="item">
 			<div class="ui grid middle aligned">
-				<div class="four wide column">
-					<div class="ui label" style="color: {{.ForegroundColor}}; background-color: {{.Color}}">{{svg "octicon-tag"}} {{.Name | RenderEmoji}}</div>
-				</div>
-				<div class="six wide column">
-					<div class="ui">
-					{{.Description | RenderEmoji}}
-					</div>
+				<div class="nine wide column">
+					{{RenderLabel .}}
+					{{if .Description}}<br><small class="desc">{{.Description | RenderEmoji}}</small>{{end}}
 				</div>
-				<div class="three wide column">
+				<div class="four wide column">
 					{{if $.PageIsOrgSettingsLabels}}
-						<a class="ui right open-issues" href="{{AppSubUrl}}/issues?labels={{.ID}}">{{svg "octicon-issue-opened"}} {{$.locale.Tr "repo.issues.label_open_issues" .NumOpenIssues}}</a>
+						<a class="ui left open-issues" href="{{AppSubUrl}}/issues?labels={{.ID}}">{{svg "octicon-issue-opened"}} {{$.locale.Tr "repo.issues.label_open_issues" .NumOpenIssues}}</a>
 					{{else}}
-						<a class="ui right open-issues" href="{{$.RepoLink}}/issues?labels={{.ID}}">{{svg "octicon-issue-opened"}} {{$.locale.Tr "repo.issues.label_open_issues" .NumOpenIssues}}</a>
+						<a class="ui left open-issues" href="{{$.RepoLink}}/issues?labels={{.ID}}">{{svg "octicon-issue-opened"}} {{$.locale.Tr "repo.issues.label_open_issues" .NumOpenIssues}}</a>
 					{{end}}
 				</div>
 				<div class="three wide column">
 					{{if and (not $.PageIsOrgSettingsLabels ) (not $.Repository.IsArchived) (or $.CanWriteIssues $.CanWritePulls)}}
 						<a class="ui right delete-button" href="#" data-url="{{$.Link}}/delete" data-id="{{.ID}}">{{svg "octicon-trash"}} {{$.locale.Tr "repo.issues.label_delete"}}</a>
-						<a class="ui right edit-label-button" href="#" data-id="{{.ID}}" data-title="{{.Name}}" data-description="{{.Description}}" data-color={{.Color}}>{{svg "octicon-pencil"}} {{$.locale.Tr "repo.issues.label_edit"}}</a>
+						<a class="ui right edit-label-button" href="#" data-id="{{.ID}}" data-title="{{.Name}}" {{if .Exclusive}}data-exclusive{{end}} data-num-issues="{{.NumIssues}}" data-description="{{.Description}}" data-color={{.Color}}>{{svg "octicon-pencil"}} {{$.locale.Tr "repo.issues.label_edit"}}</a>
 					{{else if $.PageIsOrgSettingsLabels}}
 						<a class="ui right delete-button" href="#" data-url="{{$.Link}}/delete" data-id="{{.ID}}">{{svg "octicon-trash"}} {{$.locale.Tr "repo.issues.label_delete"}}</a>
-						<a class="ui right edit-label-button" href="#" data-id="{{.ID}}" data-title="{{.Name}}" data-description="{{.Description}}" data-color={{.Color}}>{{svg "octicon-pencil"}} {{$.locale.Tr "repo.issues.label_edit"}}</a>
+						<a class="ui right edit-label-button" href="#" data-id="{{.ID}}" data-title="{{.Name}}" {{if .Exclusive}}data-exclusive{{end}} data-num-issues="{{.NumIssues}}" data-description="{{.Description}}" data-color={{.Color}}>{{svg "octicon-pencil"}} {{$.locale.Tr "repo.issues.label_edit"}}</a>
 					{{end}}
 				</div>
 			</div>
@@ -73,16 +69,12 @@
 					{{range .OrgLabels}}
 					<li class="item">
 					<div class="ui grid middle aligned">
-						<div class="three wide column">
-							<div class="ui label" style="color: {{.ForegroundColor}}; background-color: {{.Color}}">{{svg "octicon-tag"}} {{.Name | RenderEmoji}}</div>
+						<div class="nine wide column">
+							{{RenderLabel .}}
+							{{if .Description}}<br><small class="desc">{{.Description | RenderEmoji}}</small>{{end}}
 						</div>
-						<div class="seven wide column">
-							<div class="ui">
-							{{.Description | RenderEmoji}}
-							</div>
-						</div>
-						<div class="three wide column">
-								<a class="ui right open-issues" href="{{$.RepoLink}}/issues?labels={{.ID}}">{{svg "octicon-issue-opened"}} {{$.locale.Tr "repo.issues.label_open_issues" .NumOpenRepoIssues}}</a>
+						<div class="four wide column">
+							<a class="ui left open-issues" href="{{$.RepoLink}}/issues?labels={{.ID}}">{{svg "octicon-issue-opened"}} {{$.locale.Tr "repo.issues.label_open_issues" .NumOpenRepoIssues}}</a>
 						</div>
 						<div class="three wide column">
 						</div>
diff --git a/templates/repo/issue/labels/label_new.tmpl b/templates/repo/issue/labels/label_new.tmpl
index 035a4db800..62f7155b74 100644
--- a/templates/repo/issue/labels/label_new.tmpl
+++ b/templates/repo/issue/labels/label_new.tmpl
@@ -1,27 +1,47 @@
-<div class="ui new-label segment hide">
-	<form class="ui form" action="{{$.Link}}/new" method="post">
-		{{.CsrfTokenHtml}}
-		<div class="ui grid">
-			<div class="three wide column">
+<div class="ui small new-label modal">
+	<div class="header">
+		{{.locale.Tr "repo.issues.new_label"}}
+	</div>
+	<div class="content">
+		<form class="ui new-label form ignore-dirty" action="{{$.Link}}/new" method="post">
+			{{.CsrfTokenHtml}}
+			<div class="required field">
+				<label for="name">{{.locale.Tr "repo.issues.label_title"}}</label>
 				<div class="ui small input">
-					<input class="new-label-input emoji-input" name="title" placeholder="{{.locale.Tr "repo.issues.new_label_placeholder"}}" autofocus required maxlength="50">
+					<input class="label-name-input emoji-input" name="title" placeholder="{{.locale.Tr "repo.issues.new_label_placeholder"}}" autofocus required maxlength="50">
 				</div>
 			</div>
-			<div class="three wide column">
-				<div class="ui small fluid input">
-					<input class="new-label-desc-input" name="description" placeholder="{{.locale.Tr "repo.issues.new_label_desc_placeholder"}}" maxlength="200">
+			<div class="field label-exclusive-input-field">
+				<div class="ui checkbox">
+					<input class="label-exclusive-input" name="exclusive" type="checkbox">
+					<label>{{.locale.Tr "repo.issues.label_exclusive"}}</label>
 				</div>
+				<br/>
+				<small class="desc">{{.locale.Tr "repo.issues.label_exclusive_desc" | Safe}}</small>
 			</div>
-			<div class="color picker column">
-				<input class="color-picker" name="color" value="#70c24a" required maxlength="7">
-			</div>
-			<div class="column precolors">
-				{{template "repo/issue/label_precolors"}}
+			<div class="field">
+				<label for="description">{{.locale.Tr "repo.issues.label_description"}}</label>
+				<div class="ui small fluid input">
+					<input class="label-desc-input" name="description" placeholder="{{.locale.Tr "repo.issues.new_label_desc_placeholder"}}" maxlength="200">
+				</div>
 			</div>
-			<div class="buttons">
-				<div class="ui secondary small basic cancel button">{{.locale.Tr "repo.milestones.cancel"}}</div>
-				<button class="ui primary small button">{{.locale.Tr "repo.issues.create_label"}}</button>
+			<div class="field color-field">
+				<label for="color">{{$.locale.Tr "repo.issues.label_color"}}</label>
+				<div class="color picker column">
+					<input class="color-picker" name="color" value="#70c24a" required maxlength="7">
+					<div class="column precolors">
+						{{template "repo/issue/label_precolors"}}
+					</div>
+				</div>
 			</div>
+		</form>
+	</div>
+	<div class="actions">
+		<div class="ui secondary small basic cancel button">
+			{{.locale.Tr "cancel"}}
+		</div>
+		<div class="ui primary small approve button">
+			{{.locale.Tr "repo.issues.create_label"}}
 		</div>
-	</form>
+	</div>
 </div>
diff --git a/templates/repo/issue/list.tmpl b/templates/repo/issue/list.tmpl
index 4b55e7bec8..0e4969a706 100644
--- a/templates/repo/issue/list.tmpl
+++ b/templates/repo/issue/list.tmpl
@@ -50,8 +50,14 @@
 							</div>
 							<span class="info">{{.locale.Tr "repo.issues.filter_label_exclude" | Safe}}</span>
 							<a class="item" href="{{$.Link}}?q={{$.Keyword}}&type={{$.ViewType}}&sort={{$.SortType}}&state={{$.State}}&milestone={{$.MilestoneID}}&project={{$.ProjectID}}&assignee={{$.AssigneeID}}&poster={{$.PosterID}}">{{.locale.Tr "repo.issues.filter_label_no_select"}}</a>
+							{{$previousExclusiveScope := "_no_scope"}}
 							{{range .Labels}}
-								<a class="item label-filter-item" href="{{$.Link}}?q={{$.Keyword}}&type={{$.ViewType}}&sort={{$.SortType}}&state={{$.State}}&labels={{.QueryString}}&milestone={{$.MilestoneID}}&project={{$.ProjectID}}&assignee={{$.AssigneeID}}&poster={{$.PosterID}}" data-label-id="{{.ID}}">{{if .IsExcluded}}{{svg "octicon-circle-slash"}}{{else if .IsSelected}}{{svg "octicon-check"}}{{end}}<span class="label color" style="background-color: {{.Color}}"></span> {{.Name | RenderEmoji}}</a>
+								{{$exclusiveScope := .ExclusiveScope}}
+								{{if and (ne $previousExclusiveScope "_no_scope") (ne $previousExclusiveScope $exclusiveScope)}}
+									<div class="ui divider"></div>
+								{{end}}
+								{{$previousExclusiveScope = $exclusiveScope}}
+								<a class="item label-filter-item" href="{{$.Link}}?q={{$.Keyword}}&type={{$.ViewType}}&sort={{$.SortType}}&state={{$.State}}&labels={{.QueryString}}&milestone={{$.MilestoneID}}&project={{$.ProjectID}}&assignee={{$.AssigneeID}}&poster={{$.PosterID}}" data-label-id="{{.ID}}">{{if .IsExcluded}}{{svg "octicon-circle-slash"}}{{else if .IsSelected}}{{if $exclusiveScope}}{{svg "octicon-dot-fill"}}{{else}}{{svg "octicon-check"}}{{end}}{{end}} {{RenderLabel .}}</a>
 							{{end}}
 						</div>
 					</div>
@@ -217,9 +223,15 @@
 							{{svg "octicon-triangle-down" 14 "dropdown icon"}}
 						</span>
 						<div class="menu">
+							{{$previousExclusiveScope := "_no_scope"}}
 							{{range .Labels}}
+								{{$exclusiveScope := .ExclusiveScope}}
+								{{if and (ne $previousExclusiveScope "_no_scope") (ne $previousExclusiveScope $exclusiveScope)}}
+									<div class="ui divider"></div>
+								{{end}}
+								{{$previousExclusiveScope = $exclusiveScope}}
 								<div class="item issue-action" data-action="toggle" data-element-id="{{.ID}}" data-url="{{$.RepoLink}}/issues/labels">
-									{{if contain $.SelLabelIDs .ID}}{{svg "octicon-check"}}{{end}}<span class="label color" style="background-color: {{.Color}}"></span> {{.Name | RenderEmoji}}
+									{{if contain $.SelLabelIDs .ID}}{{if $exclusiveScope}}{{svg "octicon-dot-fill"}}{{else}}{{svg "octicon-check"}}{{end}}{{end}} {{RenderLabel .}}
 								</div>
 							{{end}}
 						</div>
diff --git a/templates/repo/issue/milestone_issues.tmpl b/templates/repo/issue/milestone_issues.tmpl
index 8d6a97a713..57012bddb6 100644
--- a/templates/repo/issue/milestone_issues.tmpl
+++ b/templates/repo/issue/milestone_issues.tmpl
@@ -58,7 +58,7 @@
 							<span class="info">{{.locale.Tr "repo.issues.filter_label_exclude" | Safe}}</span>
 							<a class="item" href="{{$.Link}}?q={{$.Keyword}}&type={{$.ViewType}}&sort={{$.SortType}}&state={{$.State}}&assignee={{$.AssigneeID}}&poster={{$.PosterID}}">{{.locale.Tr "repo.issues.filter_label_no_select"}}</a>
 							{{range .Labels}}
-								<a class="item label-filter-item" href="{{$.Link}}?q={{$.Keyword}}&type={{$.ViewType}}&sort={{$.SortType}}&state={{$.State}}&labels={{.QueryString}}&assignee={{$.AssigneeID}}&poster={{$.PosterID}}" data-label-id="{{.ID}}">{{if .IsExcluded}}{{svg "octicon-circle-slash"}}{{else if contain $.SelLabelIDs .ID}}{{svg "octicon-check"}}{{end}}<span class="label color" style="background-color: {{.Color}}"></span> {{.Name | RenderEmoji}}</a>
+								<a class="item label-filter-item" href="{{$.Link}}?q={{$.Keyword}}&type={{$.ViewType}}&sort={{$.SortType}}&state={{$.State}}&labels={{.QueryString}}&assignee={{$.AssigneeID}}&poster={{$.PosterID}}" data-label-id="{{.ID}}">{{if .IsExcluded}}{{svg "octicon-circle-slash"}}{{else if contain $.SelLabelIDs .ID}}{{svg "octicon-check"}}{{end}} {{RenderLabel .}}</a>
 							{{end}}
 						</div>
 					</div>
@@ -161,7 +161,7 @@
 						<div class="menu">
 							{{range .Labels}}
 								<div class="item issue-action" data-action="toggle" data-element-id="{{.ID}}" data-url="{{$.RepoLink}}/issues/labels">
-									{{if contain $.SelLabelIDs .ID}}{{svg "octicon-check"}}{{end}}<span class="label color" style="background-color: {{.Color}}"></span> {{.Name | RenderEmoji}}
+									{{if contain $.SelLabelIDs .ID}}{{svg "octicon-check"}}{{end}} {{RenderLabel .}}
 								</div>
 							{{end}}
 						</div>
diff --git a/templates/repo/issue/new_form.tmpl b/templates/repo/issue/new_form.tmpl
index 8fbd9d256a..2a6fcaa995 100644
--- a/templates/repo/issue/new_form.tmpl
+++ b/templates/repo/issue/new_form.tmpl
@@ -53,14 +53,26 @@
 					{{end}}
 					<div class="no-select item">{{.locale.Tr "repo.issues.new.clear_labels"}}</div>
 					{{if or .Labels .OrgLabels}}
+						{{$previousExclusiveScope := "_no_scope"}}
 						{{range .Labels}}
-							<a class="{{if .IsChecked}}checked{{end}} item" href="#" data-id="{{.ID}}" data-id-selector="#label_{{.ID}}"><span class="octicon-check {{if not .IsChecked}}invisible{{end}}">{{svg "octicon-check"}}</span><span class="label color" style="background-color: {{.Color}}"></span> {{.Name | RenderEmoji}}
+							{{$exclusiveScope := .ExclusiveScope}}
+							{{if and (ne $previousExclusiveScope "_no_scope") (ne $previousExclusiveScope $exclusiveScope)}}
+								<div class="ui divider"></div>
+							{{end}}
+							{{$previousExclusiveScope = $exclusiveScope}}
+							<a class="{{if .IsChecked}}checked{{end}} item" href="#" data-id="{{.ID}}" data-id-selector="#label_{{.ID}}" data-scope="{{$exclusiveScope}}"><span class="octicon-check {{if not .IsChecked}}invisible{{end}}">{{if $exclusiveScope}}{{svg "octicon-dot-fill"}}{{else}}{{svg "octicon-check"}}{{end}}</span>&nbsp;&nbsp;{{RenderLabel .}}
 							{{if .Description}}<br><small class="desc">{{.Description | RenderEmoji}}</small>{{end}}</a>
 						{{end}}
 
 						<div class="ui divider"></div>
+						{{$previousExclusiveScope := "_no_scope"}}
 						{{range .OrgLabels}}
-							<a class="{{if .IsChecked}}checked{{end}} item" href="#" data-id="{{.ID}}" data-id-selector="#label_{{.ID}}"><span class="octicon-check {{if not .IsChecked}}invisible{{end}}">{{svg "octicon-check"}}</span><span class="label color" style="background-color: {{.Color}}"></span> {{.Name | RenderEmoji}}
+							{{$exclusiveScope := .ExclusiveScope}}
+							{{if and (ne $previousExclusiveScope "_no_scope") (ne $previousExclusiveScope $exclusiveScope)}}
+								<div class="ui divider"></div>
+							{{end}}
+							{{$previousExclusiveScope = $exclusiveScope}}
+							<a class="{{if .IsChecked}}checked{{end}} item" href="#" data-id="{{.ID}}" data-id-selector="#label_{{.ID}}" data-scope="{{$exclusiveScope}}"><span class="octicon-check {{if not .IsChecked}}invisible{{end}}">{{if $exclusiveScope}}{{svg "octicon-dot-fill"}}{{else}}{{svg "octicon-check"}}{{end}}</span>&nbsp;&nbsp;{{RenderLabel .}}
 							{{if .Description}}<br><small class="desc">{{.Description | RenderEmoji}}</small>{{end}}</a>
 						{{end}}
 					{{else}}
diff --git a/templates/repo/issue/view_content/sidebar.tmpl b/templates/repo/issue/view_content/sidebar.tmpl
index 9ba46f3715..8cd34ede6e 100644
--- a/templates/repo/issue/view_content/sidebar.tmpl
+++ b/templates/repo/issue/view_content/sidebar.tmpl
@@ -123,13 +123,25 @@
 				{{end}}
 				<div class="no-select item">{{.locale.Tr "repo.issues.new.clear_labels"}}</div>
 				{{if or .Labels .OrgLabels}}
+					{{$previousExclusiveScope := "_no_scope"}}
 					{{range .Labels}}
-						<a class="{{if .IsChecked}}checked{{end}} item" href="#" data-id="{{.ID}}" data-id-selector="#label_{{.ID}}"><span class="octicon-check {{if not .IsChecked}}invisible{{end}}">{{svg "octicon-check"}}</span><span class="label color" style="background-color: {{.Color}}"></span> {{.Name | RenderEmoji}}
+						{{$exclusiveScope := .ExclusiveScope}}
+						{{if and (ne $previousExclusiveScope "_no_scope") (ne $previousExclusiveScope $exclusiveScope)}}
+							<div class="ui divider"></div>
+						{{end}}
+						{{$previousExclusiveScope = $exclusiveScope}}
+						<a class="{{if .IsChecked}}checked{{end}} item" href="#" data-id="{{.ID}}" data-id-selector="#label_{{.ID}}" data-scope="{{$exclusiveScope}}"><span class="octicon-check {{if not .IsChecked}}invisible{{end}}">{{if $exclusiveScope}}{{svg "octicon-dot-fill"}}{{else}}{{svg "octicon-check"}}{{end}}</span>&nbsp;&nbsp;{{RenderLabel .}}
 						{{if .Description}}<br><small class="desc">{{.Description | RenderEmoji}}</small>{{end}}</a>
 					{{end}}
 					<div class="ui divider"></div>
+					{{$previousExclusiveScope := "_no_scope"}}
 					{{range .OrgLabels}}
-						<a class="{{if .IsChecked}}checked{{end}} item" href="#" data-id="{{.ID}}" data-id-selector="#label_{{.ID}}"><span class="octicon-check {{if not .IsChecked}}invisible{{end}}">{{svg "octicon-check"}}</span><span class="label color" style="background-color: {{.Color}}"></span> {{.Name | RenderEmoji}}
+						{{$exclusiveScope := .ExclusiveScope}}
+						{{if and (ne $previousExclusiveScope "_no_scope") (ne $previousExclusiveScope $exclusiveScope)}}
+							<div class="ui divider"></div>
+						{{end}}
+						{{$previousExclusiveScope = $exclusiveScope}}
+						<a class="{{if .IsChecked}}checked{{end}} item" href="#" data-id="{{.ID}}" data-id-selector="#label_{{.ID}}" data-scope="{{$exclusiveScope}}"><span class="octicon-check {{if not .IsChecked}}invisible{{end}}">{{if $exclusiveScope}}{{svg "octicon-dot-fill"}}{{else}}{{svg "octicon-check"}}{{end}}</span>&nbsp;&nbsp;{{RenderLabel .}}
 						{{if .Description}}<br><small class="desc">{{.Description | RenderEmoji}}</small>{{end}}</a>
 					{{end}}
 				{{else}}
diff --git a/templates/repo/projects/view.tmpl b/templates/repo/projects/view.tmpl
index de0911e6cd..a4ada87353 100644
--- a/templates/repo/projects/view.tmpl
+++ b/templates/repo/projects/view.tmpl
@@ -245,7 +245,7 @@
 						{{if or .Labels .Assignees}}
 						<div class="extra content labels-list gt-p-0 gt-pt-2">
 							{{range .Labels}}
-								<a class="ui label" target="_blank" href="{{$.RepoLink}}/issues?labels={{.ID}}" style="color: {{.ForegroundColor}}; background-color: {{.Color}};" title="{{.Description | RenderEmojiPlain}}">{{.Name | RenderEmoji}}</a>
+								<a target="_blank" href="{{$.RepoLink}}/issues?labels={{.ID}}">{{RenderLabel .}}</a>
 							{{end}}
 							<div class="right floated">
 								{{range .Assignees}}
diff --git a/templates/shared/issuelist.tmpl b/templates/shared/issuelist.tmpl
index a246b70093..a43047c79d 100644
--- a/templates/shared/issuelist.tmpl
+++ b/templates/shared/issuelist.tmpl
@@ -42,7 +42,7 @@
 					{{end}}
 					<span class="labels-list gt-ml-2">
 						{{range .Labels}}
-							<a class="ui label" href="{{$.Link}}?q={{$.Keyword}}&type={{$.ViewType}}&state={{$.State}}&labels={{.ID}}{{if ne $.listType "milestone"}}&milestone={{$.MilestoneID}}{{end}}&assignee={{$.AssigneeID}}&poster={{$.PosterID}}" style="color: {{.ForegroundColor}}; background-color: {{.Color}}" title="{{.Description | RenderEmojiPlain}}">{{.Name | RenderEmoji}}</a>
+							<a href="{{$.Link}}?q={{$.Keyword}}&type={{$.ViewType}}&state={{$.State}}&labels={{.ID}}{{if ne $.listType "milestone"}}&milestone={{$.MilestoneID}}{{end}}&assignee={{$.AssigneeID}}&poster={{$.PosterID}}">{{RenderLabel .}}</a>
 						{{end}}
 					</span>
 				</div>
diff --git a/templates/swagger/v1_json.tmpl b/templates/swagger/v1_json.tmpl
index 00fc3b60c4..2a675766ab 100644
--- a/templates/swagger/v1_json.tmpl
+++ b/templates/swagger/v1_json.tmpl
@@ -15348,6 +15348,11 @@
           "type": "string",
           "x-go-name": "Description"
         },
+        "exclusive": {
+          "type": "boolean",
+          "x-go-name": "Exclusive",
+          "example": false
+        },
         "name": {
           "type": "string",
           "x-go-name": "Name"
@@ -16283,12 +16288,18 @@
       "properties": {
         "color": {
           "type": "string",
-          "x-go-name": "Color"
+          "x-go-name": "Color",
+          "example": "#00aabb"
         },
         "description": {
           "type": "string",
           "x-go-name": "Description"
         },
+        "exclusive": {
+          "type": "boolean",
+          "x-go-name": "Exclusive",
+          "example": false
+        },
         "name": {
           "type": "string",
           "x-go-name": "Name"
@@ -17615,6 +17626,11 @@
           "type": "string",
           "x-go-name": "Description"
         },
+        "exclusive": {
+          "type": "boolean",
+          "x-go-name": "Exclusive",
+          "example": false
+        },
         "id": {
           "type": "integer",
           "format": "int64",
diff --git a/tests/integration/api_issue_test.go b/tests/integration/api_issue_test.go
index 2f27978a37..4344c15ea4 100644
--- a/tests/integration/api_issue_test.go
+++ b/tests/integration/api_issue_test.go
@@ -174,7 +174,7 @@ func TestAPISearchIssues(t *testing.T) {
 	token := getUserToken(t, "user2")
 
 	// as this API was used in the frontend, it uses UI page size
-	expectedIssueCount := 15 // from the fixtures
+	expectedIssueCount := 16 // from the fixtures
 	if expectedIssueCount > setting.UI.IssuePagingNum {
 		expectedIssueCount = setting.UI.IssuePagingNum
 	}
@@ -198,7 +198,7 @@ func TestAPISearchIssues(t *testing.T) {
 	req = NewRequest(t, "GET", link.String())
 	resp = MakeRequest(t, req, http.StatusOK)
 	DecodeJSON(t, resp, &apiIssues)
-	assert.Len(t, apiIssues, 8)
+	assert.Len(t, apiIssues, 9)
 	query.Del("since")
 	query.Del("before")
 
@@ -214,15 +214,15 @@ func TestAPISearchIssues(t *testing.T) {
 	req = NewRequest(t, "GET", link.String())
 	resp = MakeRequest(t, req, http.StatusOK)
 	DecodeJSON(t, resp, &apiIssues)
-	assert.EqualValues(t, "17", resp.Header().Get("X-Total-Count"))
-	assert.Len(t, apiIssues, 17)
+	assert.EqualValues(t, "18", resp.Header().Get("X-Total-Count"))
+	assert.Len(t, apiIssues, 18)
 
 	query.Add("limit", "10")
 	link.RawQuery = query.Encode()
 	req = NewRequest(t, "GET", link.String())
 	resp = MakeRequest(t, req, http.StatusOK)
 	DecodeJSON(t, resp, &apiIssues)
-	assert.EqualValues(t, "17", resp.Header().Get("X-Total-Count"))
+	assert.EqualValues(t, "18", resp.Header().Get("X-Total-Count"))
 	assert.Len(t, apiIssues, 10)
 
 	query = url.Values{"assigned": {"true"}, "state": {"all"}, "token": {token}}
@@ -251,7 +251,7 @@ func TestAPISearchIssues(t *testing.T) {
 	req = NewRequest(t, "GET", link.String())
 	resp = MakeRequest(t, req, http.StatusOK)
 	DecodeJSON(t, resp, &apiIssues)
-	assert.Len(t, apiIssues, 6)
+	assert.Len(t, apiIssues, 7)
 
 	query = url.Values{"owner": {"user3"}, "token": {token}} // organization
 	link.RawQuery = query.Encode()
@@ -272,7 +272,7 @@ func TestAPISearchIssuesWithLabels(t *testing.T) {
 	defer tests.PrepareTestEnv(t)()
 
 	// as this API was used in the frontend, it uses UI page size
-	expectedIssueCount := 15 // from the fixtures
+	expectedIssueCount := 16 // from the fixtures
 	if expectedIssueCount > setting.UI.IssuePagingNum {
 		expectedIssueCount = setting.UI.IssuePagingNum
 	}
diff --git a/tests/integration/api_nodeinfo_test.go b/tests/integration/api_nodeinfo_test.go
index 6e80ebc19c..29fff8ba72 100644
--- a/tests/integration/api_nodeinfo_test.go
+++ b/tests/integration/api_nodeinfo_test.go
@@ -34,7 +34,7 @@ func TestNodeinfo(t *testing.T) {
 		assert.True(t, nodeinfo.OpenRegistrations)
 		assert.Equal(t, "gitea", nodeinfo.Software.Name)
 		assert.Equal(t, 24, nodeinfo.Usage.Users.Total)
-		assert.Equal(t, 17, nodeinfo.Usage.LocalPosts)
+		assert.Equal(t, 18, nodeinfo.Usage.LocalPosts)
 		assert.Equal(t, 2, nodeinfo.Usage.LocalComments)
 	})
 }
diff --git a/tests/integration/issue_test.go b/tests/integration/issue_test.go
index c913a2000c..eccf3c3795 100644
--- a/tests/integration/issue_test.go
+++ b/tests/integration/issue_test.go
@@ -356,7 +356,7 @@ func TestSearchIssues(t *testing.T) {
 
 	session := loginUser(t, "user2")
 
-	expectedIssueCount := 15 // from the fixtures
+	expectedIssueCount := 16 // from the fixtures
 	if expectedIssueCount > setting.UI.IssuePagingNum {
 		expectedIssueCount = setting.UI.IssuePagingNum
 	}
@@ -377,7 +377,7 @@ func TestSearchIssues(t *testing.T) {
 	req = NewRequest(t, "GET", link.String())
 	resp = session.MakeRequest(t, req, http.StatusOK)
 	DecodeJSON(t, resp, &apiIssues)
-	assert.Len(t, apiIssues, 8)
+	assert.Len(t, apiIssues, 9)
 	query.Del("since")
 	query.Del("before")
 
@@ -393,15 +393,15 @@ func TestSearchIssues(t *testing.T) {
 	req = NewRequest(t, "GET", link.String())
 	resp = session.MakeRequest(t, req, http.StatusOK)
 	DecodeJSON(t, resp, &apiIssues)
-	assert.EqualValues(t, "17", resp.Header().Get("X-Total-Count"))
-	assert.Len(t, apiIssues, 17)
+	assert.EqualValues(t, "18", resp.Header().Get("X-Total-Count"))
+	assert.Len(t, apiIssues, 18)
 
 	query.Add("limit", "5")
 	link.RawQuery = query.Encode()
 	req = NewRequest(t, "GET", link.String())
 	resp = session.MakeRequest(t, req, http.StatusOK)
 	DecodeJSON(t, resp, &apiIssues)
-	assert.EqualValues(t, "17", resp.Header().Get("X-Total-Count"))
+	assert.EqualValues(t, "18", resp.Header().Get("X-Total-Count"))
 	assert.Len(t, apiIssues, 5)
 
 	query = url.Values{"assigned": {"true"}, "state": {"all"}}
@@ -430,7 +430,7 @@ func TestSearchIssues(t *testing.T) {
 	req = NewRequest(t, "GET", link.String())
 	resp = session.MakeRequest(t, req, http.StatusOK)
 	DecodeJSON(t, resp, &apiIssues)
-	assert.Len(t, apiIssues, 6)
+	assert.Len(t, apiIssues, 7)
 
 	query = url.Values{"owner": {"user3"}} // organization
 	link.RawQuery = query.Encode()
@@ -450,7 +450,7 @@ func TestSearchIssues(t *testing.T) {
 func TestSearchIssuesWithLabels(t *testing.T) {
 	defer tests.PrepareTestEnv(t)()
 
-	expectedIssueCount := 15 // from the fixtures
+	expectedIssueCount := 16 // from the fixtures
 	if expectedIssueCount > setting.UI.IssuePagingNum {
 		expectedIssueCount = setting.UI.IssuePagingNum
 	}
diff --git a/web_src/js/components/ContextPopup.vue b/web_src/js/components/ContextPopup.vue
index 07c73ff5cf..3244034782 100644
--- a/web_src/js/components/ContextPopup.vue
+++ b/web_src/js/components/ContextPopup.vue
@@ -26,25 +26,10 @@
 <script>
 import $ from 'jquery';
 import {SvgIcon} from '../svg.js';
+import {useLightTextOnBackground} from '../utils.js';
 
 const {appSubUrl, i18n} = window.config;
 
-// NOTE: see models/issue_label.go for similar implementation
-const srgbToLinear = (color) => {
-  color /= 255;
-  if (color <= 0.04045) {
-    return color / 12.92;
-  }
-  return ((color + 0.055) / 1.055) ** 2.4;
-};
-const luminance = (colorString) => {
-  const r = srgbToLinear(parseInt(colorString.substring(0, 2), 16));
-  const g = srgbToLinear(parseInt(colorString.substring(2, 4), 16));
-  const b = srgbToLinear(parseInt(colorString.substring(4, 6), 16));
-  return 0.2126 * r + 0.7152 * g + 0.0722 * b;
-};
-const luminanceThreshold = 0.179;
-
 export default {
   components: {SvgIcon},
   data: () => ({
@@ -92,10 +77,10 @@ export default {
     labels() {
       return this.issue.labels.map((label) => {
         let textColor;
-        if (luminance(label.color) < luminanceThreshold) {
-          textColor = '#ffffff';
+        if (useLightTextOnBackground(label.color)) {
+          textColor = '#eeeeee';
         } else {
-          textColor = '#000000';
+          textColor = '#111111';
         }
         return {name: label.name, color: `#${label.color}`, textColor};
       });
diff --git a/web_src/js/features/common-issue.js b/web_src/js/features/common-issue.js
index 4a62089c60..f53dd5081b 100644
--- a/web_src/js/features/common-issue.js
+++ b/web_src/js/features/common-issue.js
@@ -32,7 +32,7 @@ export function initCommonIssue() {
     syncIssueSelectionState();
   });
 
-  $('.issue-action').on('click', async function () {
+  $('.issue-action').on('click', async function (e) {
     let action = this.getAttribute('data-action');
     let elementId = this.getAttribute('data-element-id');
     const url = this.getAttribute('data-url');
@@ -43,6 +43,9 @@ export function initCommonIssue() {
       elementId = '';
       action = 'clear';
     }
+    if (action === 'toggle' && e.altKey) {
+      action = 'toggle-alt';
+    }
     updateIssuesMeta(
       url,
       action,
diff --git a/web_src/js/features/comp/LabelEdit.js b/web_src/js/features/comp/LabelEdit.js
index df294078fa..313d406821 100644
--- a/web_src/js/features/comp/LabelEdit.js
+++ b/web_src/js/features/comp/LabelEdit.js
@@ -1,26 +1,64 @@
 import $ from 'jquery';
 import {initCompColorPicker} from './ColorPicker.js';
 
+function isExclusiveScopeName(name) {
+  return /.*[^/]\/[^/].*/.test(name);
+}
+
+function updateExclusiveLabelEdit(form) {
+  const nameInput = $(`${form} .label-name-input`);
+  const exclusiveField = $(`${form} .label-exclusive-input-field`);
+  const exclusiveCheckbox = $(`${form} .label-exclusive-input`);
+  const exclusiveWarning = $(`${form} .label-exclusive-warning`);
+
+  if (isExclusiveScopeName(nameInput.val())) {
+    exclusiveField.removeClass('muted');
+    if (exclusiveCheckbox.prop('checked') && exclusiveCheckbox.data('exclusive-warn')) {
+      exclusiveWarning.removeClass('gt-hidden');
+    } else {
+      exclusiveWarning.addClass('gt-hidden');
+    }
+  } else {
+    exclusiveField.addClass('muted');
+    exclusiveWarning.addClass('gt-hidden');
+  }
+}
+
 export function initCompLabelEdit(selector) {
   if (!$(selector).length) return;
+  initCompColorPicker();
+
   // Create label
-  const $newLabelPanel = $('.new-label.segment');
   $('.new-label.button').on('click', () => {
-    $newLabelPanel.show();
-  });
-  $('.new-label.segment .cancel').on('click', () => {
-    $newLabelPanel.hide();
+    updateExclusiveLabelEdit('.new-label');
+    $('.new-label.modal').modal({
+      onApprove() {
+        $('.new-label.form').trigger('submit');
+      }
+    }).modal('show');
+    return false;
   });
 
-  initCompColorPicker();
-
+  // Edit label
   $('.edit-label-button').on('click', function () {
     $('.edit-label .color-picker').minicolors('value', $(this).data('color'));
     $('#label-modal-id').val($(this).data('id'));
-    $('.edit-label .new-label-input').val($(this).data('title'));
-    $('.edit-label .new-label-desc-input').val($(this).data('description'));
+
+    const nameInput = $('.edit-label .label-name-input');
+    nameInput.val($(this).data('title'));
+
+    const exclusiveCheckbox = $('.edit-label .label-exclusive-input');
+    exclusiveCheckbox.prop('checked', this.hasAttribute('data-exclusive'));
+    // Warn when label was previously not exclusive and used in issues
+    exclusiveCheckbox.data('exclusive-warn',
+      $(this).data('num-issues') > 0 &&
+      (!this.hasAttribute('data-exclusive') || !isExclusiveScopeName(nameInput.val())));
+    updateExclusiveLabelEdit('.edit-label');
+
+    $('.edit-label .label-desc-input').val($(this).data('description'));
     $('.edit-label .color-picker').val($(this).data('color'));
     $('.edit-label .minicolors-swatch-color').css('background-color', $(this).data('color'));
+
     $('.edit-label.modal').modal({
       onApprove() {
         $('.edit-label.form').trigger('submit');
@@ -28,4 +66,17 @@ export function initCompLabelEdit(selector) {
     }).modal('show');
     return false;
   });
+
+  $('.new-label .label-name-input').on('input', () => {
+    updateExclusiveLabelEdit('.new-label');
+  });
+  $('.new-label .label-exclusive-input').on('change', () => {
+    updateExclusiveLabelEdit('.new-label');
+  });
+  $('.edit-label .label-name-input').on('input', () => {
+    updateExclusiveLabelEdit('.edit-label');
+  });
+  $('.edit-label .label-exclusive-input').on('change', () => {
+    updateExclusiveLabelEdit('.edit-label');
+  });
 }
diff --git a/web_src/js/features/repo-legacy.js b/web_src/js/features/repo-legacy.js
index 07c67ba5da..2cf4963b6a 100644
--- a/web_src/js/features/repo-legacy.js
+++ b/web_src/js/features/repo-legacy.js
@@ -110,35 +110,59 @@ export function initRepoCommentForm() {
       }
 
       hasUpdateAction = $listMenu.data('action') === 'update'; // Update the var
-      if ($(this).hasClass('checked')) {
-        $(this).removeClass('checked');
-        $(this).find('.octicon-check').addClass('invisible');
-        if (hasUpdateAction) {
-          if (!($(this).data('id') in items)) {
-            items[$(this).data('id')] = {
-              'update-url': $listMenu.data('update-url'),
-              action: 'detach',
-              'issue-id': $listMenu.data('issue-id'),
-            };
-          } else {
-            delete items[$(this).data('id')];
+
+      const clickedItem = $(this);
+      const scope = $(this).attr('data-scope');
+      const canRemoveScope = e.altKey;
+
+      $(this).parent().find('.item').each(function () {
+        if (scope) {
+          // Enable only clicked item for scoped labels
+          if ($(this).attr('data-scope') !== scope) {
+            return true;
           }
+          if ($(this).is(clickedItem)) {
+            if (!canRemoveScope && $(this).hasClass('checked')) {
+              return true;
+            }
+          } else if (!$(this).hasClass('checked')) {
+            return true;
+          }
+        } else if (!$(this).is(clickedItem)) {
+          // Toggle for other labels
+          return true;
         }
-      } else {
-        $(this).addClass('checked');
-        $(this).find('.octicon-check').removeClass('invisible');
-        if (hasUpdateAction) {
-          if (!($(this).data('id') in items)) {
-            items[$(this).data('id')] = {
-              'update-url': $listMenu.data('update-url'),
-              action: 'attach',
-              'issue-id': $listMenu.data('issue-id'),
-            };
-          } else {
-            delete items[$(this).data('id')];
+
+        if ($(this).hasClass('checked')) {
+          $(this).removeClass('checked');
+          $(this).find('.octicon-check').addClass('invisible');
+          if (hasUpdateAction) {
+            if (!($(this).data('id') in items)) {
+              items[$(this).data('id')] = {
+                'update-url': $listMenu.data('update-url'),
+                action: 'detach',
+                'issue-id': $listMenu.data('issue-id'),
+              };
+            } else {
+              delete items[$(this).data('id')];
+            }
+          }
+        } else {
+          $(this).addClass('checked');
+          $(this).find('.octicon-check').removeClass('invisible');
+          if (hasUpdateAction) {
+            if (!($(this).data('id') in items)) {
+              items[$(this).data('id')] = {
+                'update-url': $listMenu.data('update-url'),
+                action: 'attach',
+                'issue-id': $listMenu.data('issue-id'),
+              };
+            } else {
+              delete items[$(this).data('id')];
+            }
           }
         }
-      }
+      });
 
       // TODO: Which thing should be done for choosing review requests
       // to make chosen items be shown on time here?
diff --git a/web_src/js/features/repo-projects.js b/web_src/js/features/repo-projects.js
index f6d6c89816..534f517853 100644
--- a/web_src/js/features/repo-projects.js
+++ b/web_src/js/features/repo-projects.js
@@ -1,4 +1,5 @@
 import $ from 'jquery';
+import {useLightTextOnBackground} from '../utils.js';
 
 const {csrfToken} = window.config;
 
@@ -183,26 +184,13 @@ export function initRepoProject() {
 }
 
 function setLabelColor(label, color) {
-  const red = getRelativeColor(parseInt(color.slice(1, 3), 16));
-  const green = getRelativeColor(parseInt(color.slice(3, 5), 16));
-  const blue = getRelativeColor(parseInt(color.slice(5, 7), 16));
-  const luminance = 0.2126 * red + 0.7152 * green + 0.0722 * blue;
-
-  if (luminance > 0.179) {
-    label.removeClass('light-label').addClass('dark-label');
-  } else {
+  if (useLightTextOnBackground(color)) {
     label.removeClass('dark-label').addClass('light-label');
+  } else {
+    label.removeClass('light-label').addClass('dark-label');
   }
 }
 
-/**
- * Inspired by W3C recommendation https://www.w3.org/TR/WCAG20/#relativeluminancedef
- */
-function getRelativeColor(color) {
-  color /= 255;
-  return color <= 0.03928 ? color / 12.92 : ((color + 0.055) / 1.055) ** 2.4;
-}
-
 function rgbToHex(rgb) {
   rgb = rgb.match(/^rgba?\((\d+),\s*(\d+),\s*(\d+).*\)$/);
   return `#${hex(rgb[1])}${hex(rgb[2])}${hex(rgb[3])}`;
diff --git a/web_src/js/utils.js b/web_src/js/utils.js
index c7624404c7..b3ffbf2988 100644
--- a/web_src/js/utils.js
+++ b/web_src/js/utils.js
@@ -146,3 +146,18 @@ export function toAbsoluteUrl(url) {
   }
   return `${window.location.origin}${url}`;
 }
+
+// determine if light or dark text color should be used on a given background color
+// NOTE: see models/issue_label.go for similar implementation
+export function useLightTextOnBackground(backgroundColor) {
+  if (backgroundColor[0] === '#') {
+    backgroundColor = backgroundColor.substring(1);
+  }
+  // Perceived brightness from: https://www.w3.org/TR/AERT/#color-contrast
+  // In the future WCAG 3 APCA may be a better solution.
+  const r = parseInt(backgroundColor.substring(0, 2), 16);
+  const g = parseInt(backgroundColor.substring(2, 4), 16);
+  const b = parseInt(backgroundColor.substring(4, 6), 16);
+  const brightness = (0.299 * r + 0.587 * g + 0.114 * b) / 255;
+  return brightness < 0.35;
+}
diff --git a/web_src/less/_base.less b/web_src/less/_base.less
index 4b65ae6812..771049ad39 100644
--- a/web_src/less/_base.less
+++ b/web_src/less/_base.less
@@ -1116,6 +1116,7 @@ a.ui.card:hover,
 
 .ui.modal > .content {
   background: var(--color-body);
+  text-align: left !important;
 }
 
 .ui.modal > .actions {
@@ -1364,6 +1365,10 @@ a.ui.card:hover,
   -webkit-text-fill-color: var(--color-black) !important;
 }
 
+.ui.form .field.muted {
+  opacity: var(--opacity-disabled);
+}
+
 .ui.loading.loading.input > i.icon svg {
   visibility: hidden;
 }
@@ -2568,8 +2573,7 @@ table th[data-sortt-desc] {
     border-top: none;
 
     a {
-      font-size: 15px;
-      padding-top: 5px;
+      font-size: 12px;
       padding-right: 10px;
       color: var(--color-text-light);
 
@@ -2581,10 +2585,6 @@ table th[data-sortt-desc] {
         margin-right: 30px;
       }
     }
-
-    .ui.label {
-      font-size: 1em;
-    }
   }
 
   .item:last-child {
diff --git a/web_src/less/_repository.less b/web_src/less/_repository.less
index f7087d4d30..b2c4cdcdfb 100644
--- a/web_src/less/_repository.less
+++ b/web_src/less/_repository.less
@@ -92,7 +92,7 @@
   .metas {
     .menu {
       overflow-x: auto;
-      max-height: 300px;
+      max-height: 500px;
     }
 
     .ui.list {
@@ -155,12 +155,6 @@
   }
 
   .filter.menu {
-    .label.color {
-      border-radius: 3px;
-      margin-left: 15px;
-      padding: 0 8px;
-    }
-
     &.labels {
       .label-filter .menu .info {
         display: inline-block;
@@ -181,7 +175,7 @@
     }
 
     .menu {
-      max-height: 300px;
+      max-height: 500px;
       overflow-x: auto;
       right: 0 !important;
       left: auto !important;
@@ -190,7 +184,7 @@
 
   .select-label {
     .desc {
-      padding-left: 16px;
+      padding-left: 23px;
     }
   }
 
@@ -607,7 +601,7 @@
         min-width: 220px;
 
         .filter.menu {
-          max-height: 300px;
+          max-height: 500px;
           overflow-x: auto;
         }
       }
@@ -2774,7 +2768,7 @@
 }
 
 .edit-label.modal,
-.new-label.segment {
+.new-label.modal {
   .form {
     .column {
       padding-right: 0;
@@ -2786,12 +2780,9 @@
     }
 
     .color.picker.column {
-      width: auto;
-
-      .color-picker {
-        height: 35px;
-        width: auto;
-        padding-left: 30px;
+      display: flex;
+      .minicolors {
+        flex: 1;
       }
     }
 
@@ -2872,6 +2863,35 @@
   line-height: 1.3em; // there is a `font-size: 1.25em` for inside emoji, so here the line-height needs to be larger slightly
 }
 
+// Scoped labels with different colors on left and right, and slanted divider in the middle
+.scope-parent {
+  background: none !important;
+  padding: 0 !important;
+}
+
+.ui.label.scope-left {
+  border-bottom-right-radius: 0;
+  border-top-right-radius: 0;
+  padding-right: 0;
+  margin-right: 0;
+}
+
+.ui.label.scope-middle {
+  width: 12px;
+  border-radius: 0;
+  padding-left: 0;
+  padding-right: 0;
+  margin-left: 0;
+  margin-right: 0;
+}
+
+.ui.label.scope-right {
+  border-bottom-left-radius: 0;
+  border-top-left-radius: 0;
+  padding-left: 0;
+  margin-left: 0;
+}
+
 .repo-button-row {
   margin-bottom: 10px;
 }