Window decorations: added client property to mark components in embed…

…ded menu bar as "caption" (issue #569)

CHANGELOG.md

@@ -7,6 +7,9 @@ FlatLaf Change Log
 
 - TabbedPane: New option to disable tab run rotation in wrap layout. Set UI
   value `TabbedPane.rotateTabRuns` to `false`. (issue #574)
+- Native window decorations (Windows 10/11 only): Added client property to mark
+  components in embedded menu bar as "caption" (allow moving window). (issue
+  #569)
 
 #### Fixed bugs
 

flatlaf-core/src/main/java/com/formdev/flatlaf/FlatClientProperties.java

@@ -253,6 +253,19 @@ public interface FlatClientProperties
 	 */
 	String COMPONENT_FOCUS_OWNER = "JComponent.focusOwner";
 
+	/**
+	 * Specifies whether a component in a embedded menu bar should behave as caption
+	 * (left-click allows moving window, right-click shows window system menu).
+	 * The component does not receive mouse pressed/released/clicked/dragged events,
+	 * but it gets mouse entered/exited/moved events.
+	 * <p>
+	 * <strong>Component</strong> {@link javax.swing.JComponent}<br>
+	 * <strong>Value type</strong> {@link java.lang.Boolean}
+	 *
+	 * @since 2.5
+	 */
+	String COMPONENT_TITLE_BAR_CAPTION = "JComponent.titleBarCaption";
+
 	//---- Popup --------------------------------------------------------------
 
 	/**

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

@@ -861,26 +861,32 @@ protected void updateNativeTitleBarHeightAndHitTestSpots() {
 					r.height -= resizeHeight;
 				}
 
-				Component horizontalGlue = findHorizontalGlue( menuBar );
-				if( horizontalGlue != null ) {
-					// If menu bar is embedded and contains a horizontal glue component,
-					// then split the hit test spot into two spots so that
-					// the glue component area can be used to move the window.
-
-					Point glueLocation = SwingUtilities.convertPoint( horizontalGlue, 0, 0, window );
-					int x2 = glueLocation.x + horizontalGlue.getWidth();
-					Rectangle r2;
-					if( getComponentOrientation().isLeftToRight() ) {
-						r2 = new Rectangle( x2, r.y, (r.x + r.width) - x2, r.height );
-
-						r.width = glueLocation.x - r.x;
-					} else {
-						r2 = new Rectangle( r.x, r.y, glueLocation.x - r.x, r.height );
-
-						r.width = (r.x + r.width) - x2;
-						r.x = x2;
+				int count = menuBar.getComponentCount();
+				for( int i = count - 1; i >= 0; i-- ) {
+					Component c = menuBar.getComponent( i );
+					if( c instanceof Box.Filler ||
+						(c instanceof JComponent && clientPropertyBoolean( (JComponent) c, COMPONENT_TITLE_BAR_CAPTION, false ) ) )
+					{
+						// If menu bar is embedded and contains a horizontal glue or caption component,
+						// then split the hit test spot so that
+						// the glue/caption component area can be used to move the window.
+
+						Point glueLocation = SwingUtilities.convertPoint( c, 0, 0, window );
+						int x2 = glueLocation.x + c.getWidth();
+						Rectangle r2;
+						if( getComponentOrientation().isLeftToRight() ) {
+							r2 = new Rectangle( x2, r.y, (r.x + r.width) - x2, r.height );
+
+							r.width = glueLocation.x - r.x;
+						} else {
+							r2 = new Rectangle( r.x, r.y, glueLocation.x - r.x, r.height );
+
+							r.width = (r.x + r.width) - x2;
+							r.x = x2;
+						}
+						if( r2.width > 0 )
+							hitTestSpots.add( r2 );
 					}
-					hitTestSpots.add( r2 );
 				}
 
 				hitTestSpots.add( r );

flatlaf-testing/src/main/java/com/formdev/flatlaf/testing/FlatWindowDecorationsTest.java

@@ -262,6 +262,16 @@ protected void paintComponent( Graphics g ) {
 		menuBar.revalidate();
 	}
 
+	private void addCaption() {
+		JLabel caption = new JLabel( "Caption" );
+		caption.setBackground( Color.green );
+		caption.setOpaque( true );
+		caption.putClientProperty( FlatClientProperties.COMPONENT_TITLE_BAR_CAPTION, true );
+
+		menuBar.add( caption );
+		menuBar.revalidate();
+	}
+
 	private void removeMenu() {
 		int menuCount = menuBar.getMenuCount();
 		if( menuCount <= 0 )
@@ -445,6 +455,7 @@ private void initComponents() {
 		JPanel panel3 = new JPanel();
 		addMenuButton = new JButton();
 		addGlueButton = new JButton();
+		addCaptionButton = new JButton();
 		removeMenuButton = new JButton();
 		changeMenuButton = new JButton();
 		changeTitleButton = new JButton();
@@ -547,6 +558,7 @@ private void initComponents() {
 				"[]" +
 				"[]" +
 				"[]" +
+				"[]" +
 				"[]unrel" +
 				"[]"));
 
@@ -560,20 +572,25 @@ private void initComponents() {
 			addGlueButton.addActionListener(e -> addGlue());
 			panel3.add(addGlueButton, "cell 0 1");
 
+			//---- addCaptionButton ----
+			addCaptionButton.setText("Add caption");
+			addCaptionButton.addActionListener(e -> addCaption());
+			panel3.add(addCaptionButton, "cell 0 2");
+
 			//---- removeMenuButton ----
 			removeMenuButton.setText("Remove menu");
 			removeMenuButton.addActionListener(e -> removeMenu());
-			panel3.add(removeMenuButton, "cell 0 2");
+			panel3.add(removeMenuButton, "cell 0 3");
 
 			//---- changeMenuButton ----
 			changeMenuButton.setText("Change menu");
 			changeMenuButton.addActionListener(e -> changeMenu());
-			panel3.add(changeMenuButton, "cell 0 3");
+			panel3.add(changeMenuButton, "cell 0 4");
 
 			//---- changeTitleButton ----
 			changeTitleButton.setText("Change title");
 			changeTitleButton.addActionListener(e -> changeTitle());
-			panel3.add(changeTitleButton, "cell 0 4");
+			panel3.add(changeTitleButton, "cell 0 5");
 		}
 		add(panel3, "cell 2 0 1 8,aligny top,growy 0");
 
@@ -961,6 +978,7 @@ private void initComponents() {
 	private JCheckBox rightCompCheckBox;
 	private JButton addMenuButton;
 	private JButton addGlueButton;
+	private JButton addCaptionButton;
 	private JButton removeMenuButton;
 	private JButton changeMenuButton;
 	private JButton changeTitleButton;

flatlaf-testing/src/main/java/com/formdev/flatlaf/testing/FlatWindowDecorationsTest.jfd

@@ -36,7 +36,7 @@ new FormModel {
 			add( new FormContainer( "javax.swing.JPanel", new FormLayoutManager( class net.miginfocom.swing.MigLayout ) {
 				"$layoutConstraints": "hidemode 3"
 				"$columnConstraints": "[fill]"
-				"$rowConstraints": "[][][][]unrel[]"
+				"$rowConstraints": "[][][][][]unrel[]"
 			} ) {
 				name: "panel3"
 				add( new FormComponent( "javax.swing.JButton" ) {
@@ -59,6 +59,16 @@ new FormModel {
 				}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
 					"value": "cell 0 1"
 				} )
+				add( new FormComponent( "javax.swing.JButton" ) {
+					name: "addCaptionButton"
+					"text": "Add caption"
+					auxiliary() {
+						"JavaCodeGenerator.variableLocal": false
+					}
+					addEvent( new FormEvent( "java.awt.event.ActionListener", "actionPerformed", "addCaption", false ) )
+				}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
+					"value": "cell 0 2"
+				} )
 				add( new FormComponent( "javax.swing.JButton" ) {
 					name: "removeMenuButton"
 					"text": "Remove menu"
@@ -67,7 +77,7 @@ new FormModel {
 					}
 					addEvent( new FormEvent( "java.awt.event.ActionListener", "actionPerformed", "removeMenu", false ) )
 				}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
-					"value": "cell 0 2"
+					"value": "cell 0 3"
 				} )
 				add( new FormComponent( "javax.swing.JButton" ) {
 					name: "changeMenuButton"
@@ -77,7 +87,7 @@ new FormModel {
 					}
 					addEvent( new FormEvent( "java.awt.event.ActionListener", "actionPerformed", "changeMenu", false ) )
 				}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
-					"value": "cell 0 3"
+					"value": "cell 0 4"
 				} )
 				add( new FormComponent( "javax.swing.JButton" ) {
 					name: "changeTitleButton"
@@ -87,7 +97,7 @@ new FormModel {
 					}
 					addEvent( new FormEvent( "java.awt.event.ActionListener", "actionPerformed", "changeTitle", false ) )
 				}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
-					"value": "cell 0 4"
+					"value": "cell 0 5"
 				} )
 			}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
 				"value": "cell 2 0 1 8,aligny top,growy 0"