Merge PR #1030: TabbedPaneUI: When the mouse wheel event is not in the viewport, propagate the event to the nearest parent

CHANGELOG.md

@@ -11,6 +11,9 @@ FlatLaf Change Log
 - TabbedPane: Added icon-only tab mode, which shows tab icons but hides tab
   titles. Tab titles are used in "Show Hidden Tabs" popup menu. (set client
   property `JTabbedPane.tabWidthMode` to `"iconOnly"`)
+- TabbedPane: In scroll tab layout, propagate mouse wheel events to ancestors.
+  This allows mouse wheel scrolling if JTabbedPane is inside a JScrollPane. (PR
+  #1030)
 
 #### Fixed bugs
 

flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatTabbedPaneUI.java

@@ -2718,8 +2718,13 @@ debug*/
 
 			// because this listener receives mouse events for the whole tabbed pane,
 			// we have to check whether the mouse is located over the viewport
-			if( !isInViewport( e.getX(), e.getY() ) )
+			if( !isInViewport( e.getX(), e.getY() ) ) {
+				// if it is not in the viewport, retarget the event to a parent container
+				// which might support scrolling (e.g. a surrounding ScrollPane)
+				Container parent = tabPane.getParent();
+				parent.dispatchEvent( SwingUtilities.convertMouseEvent( tabPane, e, parent ) );
 				return;
+			}
 
 			lastMouseX = e.getX();
 			lastMouseY = e.getY();