Test

docking-api/src/ModernDocking/floating/FloatUtilsFrame.java

@@ -52,6 +52,20 @@ public class FloatUtilsFrame extends JFrame implements DragSourceMotionListener,
     private DockableHandles dockableHandles;
 
     BufferStrategy bs; //create an strategy for multi-buffering.
+    JPanel renderPanel = new JPanel() {
+        @Override
+        protected void paintComponent(Graphics g) {
+            Graphics2D g2 = (Graphics2D) g.create();
+            rootHandles.paint(g2);
+
+            if (dockableHandles != null) {
+                dockableHandles.paint(g2);
+            }
+
+            overlay.paint(g);
+            g2.dispose();
+        }
+    };
 
     public FloatUtilsFrame(DockingAPI docking, Window referenceDockingWindow, InternalRootDockingPanel root) {
         this.referenceDockingWindow = referenceDockingWindow;
@@ -72,6 +86,14 @@ public FloatUtilsFrame(DockingAPI docking, Window referenceDockingWindow, Intern
         getRootPane().setBackground(new Color(0, 0, 0, 0)); // don't want a background for the root pane either. Workaround for a FlatLaf macOS issue.
         getContentPane().setBackground(new Color(0, 0, 0, 0)); // don't want a background for the content frame either.
 
+        GraphicsConfiguration gc = GraphicsEnvironment.getLocalGraphicsEnvironment().getDefaultScreenDevice().getDefaultConfiguration();
+        BufferCapabilities bufferCapabilities = gc.getBufferCapabilities();
+
+        if (bufferCapabilities.isMultiBufferAvailable()) {
+            add(renderPanel);
+            renderPanel.setOpaque(false);
+        }
+
         try {
             if (getContentPane() instanceof JComponent) {
                 ((JComponent) getContentPane()).setOpaque(false);
@@ -98,8 +120,14 @@ public void activate(FloatListener floatListener, JFrame floatingFrame, DragSour
 
         setVisible(true);
 
-        createBufferStrategy(2);
-        bs = this.getBufferStrategy();
+        GraphicsConfiguration gc = GraphicsEnvironment.getLocalGraphicsEnvironment().getDefaultScreenDevice().getDefaultConfiguration();
+        BufferCapabilities bufferCapabilities = gc.getBufferCapabilities();
+
+        if (!bufferCapabilities.isMultiBufferAvailable()) {
+            createBufferStrategy(2);
+            bs = this.getBufferStrategy();
+        }
+
         orderFrames();
     }
 
@@ -210,19 +238,27 @@ private void orderFrames() {
     }
 
     @Override
-    public void paint(Graphics gf) {
-        if (bs == null) return;
-        Graphics g = bs.getDrawGraphics();
+    public void paint(Graphics g) {
+        if (bs == null) {
+            super.paint(g);
+            return;
+        }
+
+        g = bs.getDrawGraphics();
         Graphics2D g2 = (Graphics2D) bs.getDrawGraphics();
 
         g2.clearRect(0, 0, getWidth(), getHeight());
 
         rootHandles.paint(g2);
+
         if (dockableHandles != null) {
             dockableHandles.paint(g2);
         }
+
         overlay.paint(g);
+
         g2.dispose();
+
         bs.show();
     }
 
@@ -298,6 +334,8 @@ private void setSizeAndLocation() {
         setLocation(location);
         setSize(size);
 
+        renderPanel.setSize(size);
+
         rootHandles.updateHandlePositions();
 
         revalidate();