Scroll the parent if Grid has already scrolled to the end (#10700)

Fixes #9477

client/src/main/java/com/vaadin/client/widgets/Escalator.java

@@ -568,7 +568,6 @@ public class Escalator extends Widget
                     yMov.moveTouch(event);
                     xMov.validate(yMov);
                     yMov.validate(xMov);
-                    event.getNativeEvent().preventDefault();
                     moveScrollFromEvent(escalator, xMov.delta, yMov.delta,
                             event.getNativeEvent());
                 }
@@ -620,21 +619,36 @@ public class Escalator extends Widget
                 final double deltaX, final double deltaY,
                 final NativeEvent event) {
 
+            boolean scrollPosXChanged = false;
+            boolean scrollPosYChanged = false;
+
             if (!Double.isNaN(deltaX)) {
+                double oldScrollPosX = escalator.horizontalScrollbar
+                        .getScrollPos();
                 escalator.horizontalScrollbar.setScrollPosByDelta(deltaX);
+                if (oldScrollPosX != escalator.horizontalScrollbar
+                        .getScrollPos()) {
+                    scrollPosXChanged = true;
+                }
             }
 
             if (!Double.isNaN(deltaY)) {
+                double oldScrollPosY = escalator.verticalScrollbar
+                        .getScrollPos();
                 escalator.verticalScrollbar.setScrollPosByDelta(deltaY);
+                if (oldScrollPosY != escalator.verticalScrollbar
+                        .getScrollPos()) {
+                    scrollPosYChanged = true;
+                }
             }
 
             /*
-             * TODO: only prevent if not scrolled to end/bottom. Or no? UX team
-             * needs to decide.
+             * Only prevent if internal scrolling happened. If there's no more
+             * room to scroll internally, allow the event to pass further.
              */
-            final boolean warrantedYScroll = deltaY != 0
+            final boolean warrantedYScroll = deltaY != 0 && scrollPosYChanged
                     && escalator.verticalScrollbar.showsScrollHandle();
-            final boolean warrantedXScroll = deltaX != 0
+            final boolean warrantedXScroll = deltaX != 0 && scrollPosXChanged
                     && escalator.horizontalScrollbar.showsScrollHandle();
             if (warrantedYScroll || warrantedXScroll) {
                 event.preventDefault();

uitest/src/main/java/com/vaadin/tests/components/grid/GridScrollOuterLayoutAfterContents.java

@@ -0,0 +1,52 @@
+package com.vaadin.tests.components.grid;
+
+import java.util.stream.IntStream;
+
+import com.vaadin.annotations.Widgetset;
+import com.vaadin.server.VaadinRequest;
+import com.vaadin.shared.ui.grid.HeightMode;
+import com.vaadin.tests.components.AbstractTestUI;
+import com.vaadin.ui.Grid;
+import com.vaadin.ui.Panel;
+import com.vaadin.ui.TextArea;
+import com.vaadin.ui.VerticalLayout;
+
+@Widgetset("com.vaadin.DefaultWidgetSet")
+public class GridScrollOuterLayoutAfterContents extends AbstractTestUI {
+
+    @Override
+    protected void setup(VaadinRequest request) {
+        Grid<Integer> grid = new Grid<>();
+
+        // create column and fill rows
+        grid.addColumn(item -> "name" + item).setCaption("Name");
+        grid.addColumn(item -> "content" + item).setCaption("Content");
+        grid.setItems(IntStream.range(1, 21).boxed());
+
+        // set height mode and height
+        grid.setHeightMode(HeightMode.ROW);
+        grid.setHeightByRows(10);
+
+        VerticalLayout layout = new VerticalLayout(grid, new TextArea());
+        layout.setSpacing(true);
+        layout.setMargin(false);
+        layout.setSizeUndefined();
+
+        Panel panel = new Panel();
+        panel.setContent(layout);
+        panel.setHeight("200px");
+        panel.setWidthUndefined();
+
+        addComponent(panel);
+    }
+
+    @Override
+    protected String getTestDescription() {
+        return "Should be possible to scroll to the TextArea underneath the Grid even on mobile";
+    }
+
+    @Override
+    protected Integer getTicketNumber() {
+        return 9477;
+    }
+}