Focus click element inside a drag'n'drop wrapper (#14826)

Focus inside a drag'n'drop wrapper does not work out of the box as mousedown is 
cancelled to avoid text selection when starting a dnd operation.

This change explicitly calls focus on the element at the location which was clicked.

Input elements will now be able to gain focus but e.g. clicking to move the caret 
inside a text area won't work as mousedown is cancelled.

Change-Id: I89e046ddb0b1044bc6a2f11fda4edbe5fda25743

1 files changed, 4 insertions, 16 deletions

diff --git a/client/src/com/vaadin/client/ui/VDragAndDropWrapper.java b/client/src/com/vaadin/client/ui/VDragAndDropWrapper.java
index d0584d150a..15ab9a6ce0 100644
--- a/client/src/com/vaadin/client/ui/VDragAndDropWrapper.java
+++ b/client/src/com/vaadin/client/ui/VDragAndDropWrapper.java
@@ -45,6 +45,7 @@ import com.vaadin.client.MouseEventDetailsBuilder;
 import com.vaadin.client.Util;
 import com.vaadin.client.VConsole;
 import com.vaadin.client.ValueMap;
+import com.vaadin.client.WidgetUtil;
 import com.vaadin.client.ui.dd.DDUtil;
 import com.vaadin.client.ui.dd.VAbstractDropHandler;
 import com.vaadin.client.ui.dd.VAcceptCallback;
@@ -106,25 +107,12 @@ public class VDragAndDropWrapper extends VCustomComponent implements
                 final int deltaX = Math.abs(event.getClientX() - startX);
                 final int deltaY = Math.abs(event.getClientY() - startY);
                 if ((deltaX + deltaY) < MIN_PX_DELTA) {
-                    setFocusOnLastElement(event);
+                    Element clickedElement = WidgetUtil.getElementFromPoint(
+                            event.getClientX(), event.getClientY());
+                    clickedElement.focus();
                 }
             }
 
-            private void setFocusOnLastElement(final MouseUpEvent event) {
-                Element el = event.getRelativeElement();
-                getLastChildElement(el).focus();
-            }
-
-            private Element getLastChildElement(Element el) {
-                do {
-                    if (el == null) {
-                        break;
-                    }
-                    el = el.getFirstChildElement();
-                } while (el.getFirstChildElement() != null);
-                return el;
-            }
-
         }, MouseUpEvent.getType());
 
         addDomHandler(new TouchStartHandler() {