diff --git a/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatRootPaneUI.java b/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatRootPaneUI.java
index c812f993..db5fa9c5 100644
--- a/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatRootPaneUI.java
+++ b/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatRootPaneUI.java
@@ -48,11 +48,25 @@ import com.formdev.flatlaf.util.SystemInfo;
 /**
  * Provides the Flat LaF UI delegate for {@link javax.swing.JRootPane}.
  *
+ * <!-- FlatRootPaneUI -->
+ *
+ * @uiDefault RootPane.border								Border
+ *
+ * <!-- FlatWindowResizer -->
+ *
+ * @uiDefault RootPane.borderDragThickness					int
+ * @uiDefault RootPane.cornerDragWidth						int
+ * @uiDefault RootPane.honorMinimumSizeOnResize				boolean
+ *
  * @author Karl Tauber
  */
 public class FlatRootPaneUI
 	extends BasicRootPaneUI
 {
+	// check this field before using class JBRCustomDecorations to avoid unnecessary loading of that class
+	static final boolean canUseJBRCustomDecorations
+		= SystemInfo.IS_JETBRAINS_JVM_11_OR_LATER && SystemInfo.IS_WINDOWS_10_OR_LATER;
+
 	private JRootPane rootPane;
 	private FlatTitlePane titlePane;
 	private LayoutManager oldLayout;
@@ -71,7 +85,7 @@ public class FlatRootPaneUI
 		if( rootPane.getWindowDecorationStyle() != JRootPane.NONE )
 			installClientDecorations();
 
-		if( SystemInfo.IS_JETBRAINS_JVM_11_OR_LATER && SystemInfo.IS_WINDOWS_10_OR_LATER )
+		if( canUseJBRCustomDecorations )
 			JBRCustomDecorations.install( rootPane );
 	}
 
@@ -108,8 +122,10 @@ public class FlatRootPaneUI
 	}
 
 	private void installClientDecorations() {
+		boolean isJBRSupported = canUseJBRCustomDecorations && JBRCustomDecorations.isSupported();
+
 		// install border
-		if( rootPane.getWindowDecorationStyle() != JRootPane.NONE && !JBRCustomDecorations.isSupported() )
+		if( rootPane.getWindowDecorationStyle() != JRootPane.NONE && !isJBRSupported )
 			LookAndFeel.installBorder( rootPane, "RootPane.border" );
 		else
 			LookAndFeel.uninstallBorder( rootPane );
@@ -122,7 +138,7 @@ public class FlatRootPaneUI
 		rootPane.setLayout( new FlatRootLayout() );
 
 		// install window resizer
-		if( !JBRCustomDecorations.isSupported() )
+		if( !isJBRSupported )
 			windowResizer = new FlatWindowResizer( rootPane );
 	}
 
diff --git a/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatTitlePane.java b/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatTitlePane.java
index 399d1949..793027cd 100644
--- a/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatTitlePane.java
+++ b/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatTitlePane.java
@@ -446,7 +446,9 @@ class FlatTitlePane
 	}
 
 	private boolean hasJBRCustomDecoration() {
-		return window != null && JBRCustomDecorations.hasCustomDecoration( window );
+		return window != null &&
+			FlatRootPaneUI.canUseJBRCustomDecorations &&
+			JBRCustomDecorations.hasCustomDecoration( window );
 	}
 
 	private void updateJBRHitTestSpotsAndTitleBarHeight() {
diff --git a/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/JBRCustomDecorations.java b/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/JBRCustomDecorations.java
index 2ded0eb8..d06069f8 100644
--- a/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/JBRCustomDecorations.java
+++ b/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/JBRCustomDecorations.java
@@ -68,65 +68,26 @@ public class JBRCustomDecorations
 	}
 
 	static void install( JRootPane rootPane ) {
-		boolean frameIsDefaultLookAndFeelDecorated = JFrame.isDefaultLookAndFeelDecorated();
-		boolean dialogIsDefaultLookAndFeelDecorated = JDialog.isDefaultLookAndFeelDecorated();
-		boolean lafSupportsWindowDecorations = UIManager.getLookAndFeel().getSupportsWindowDecorations();
-
-		// check whether decorations are enabled
-		if( !frameIsDefaultLookAndFeelDecorated && !dialogIsDefaultLookAndFeelDecorated )
-			return;
-
-		// do not enable JBR decorations if JFrame and JDialog will use LaF decorations
-		if( lafSupportsWindowDecorations &&
-			frameIsDefaultLookAndFeelDecorated &&
-			dialogIsDefaultLookAndFeelDecorated )
-		  return;
-
 		if( !isSupported() )
 			return;
 
-		// use hierarchy listener to wait until the root pane is added to a window
+		// check whether root pane already has a parent, which is the case when switching LaF
+		if( rootPane.getParent() != null )
+			return;
+
+		// Use hierarchy listener to wait until the root pane is added to a window.
+		// Enabling JBR decorations must be done very early, probably before
+		// window becomes displayable (window.isDisplayable()). Tried also using
+		// "ancestor" property change event on root pane, but this is invoked too late.
 		HierarchyListener addListener = new HierarchyListener() {
 			@Override
 			public void hierarchyChanged( HierarchyEvent e ) {
-				if( (e.getChangeFlags() & HierarchyEvent.PARENT_CHANGED) == 0 )
+				if( e.getChanged() != rootPane || (e.getChangeFlags() & HierarchyEvent.PARENT_CHANGED) == 0 )
 					return;
 
 				Container parent = e.getChangedParent();
-				if( parent instanceof JFrame ) {
-					JFrame frame = (JFrame) parent;
-
-					// do not enable JBR decorations if JFrame will use LaF decorations
-					if( lafSupportsWindowDecorations && frameIsDefaultLookAndFeelDecorated )
-						return;
-
-					// do not enable JBR decorations if frame is undecorated
-					if( frame.isUndecorated() )
-						return;
-
-					// enable JBR custom window decoration for window
-					setHasCustomDecoration( frame );
-
-					// enable Swing window decoration
-					rootPane.setWindowDecorationStyle( JRootPane.FRAME );
-
-				} else if( parent instanceof JDialog ) {
-					JDialog dialog = (JDialog)parent;
-
-					// do not enable JBR decorations if JDialog will use LaF decorations
-					if( lafSupportsWindowDecorations && dialogIsDefaultLookAndFeelDecorated )
-						return;
-
-					// do not enable JBR decorations if dialog is undecorated
-					if( dialog.isUndecorated() )
-						return;
-
-					// enable JBR custom window decoration for window
-					setHasCustomDecoration( dialog );
-
-					// enable Swing window decoration
-					rootPane.setWindowDecorationStyle( JRootPane.PLAIN_DIALOG );
-				}
+				if( parent instanceof Window )
+					install( (Window) parent );
 
 				// use invokeLater to remove listener to avoid that listener
 				// is removed while listener queue is processed
@@ -138,6 +99,50 @@ public class JBRCustomDecorations
 		rootPane.addHierarchyListener( addListener );
 	}
 
+	static void install( Window window ) {
+		if( !isSupported() )
+			return;
+
+		// do not enable JBR decorations if LaF provides decorations
+		if( UIManager.getLookAndFeel().getSupportsWindowDecorations() )
+			return;
+
+		if( window instanceof JFrame ) {
+			JFrame frame = (JFrame) window;
+
+			// do not enable JBR decorations if JFrame should use system window decorations
+			if( !JFrame.isDefaultLookAndFeelDecorated()  )
+				return;
+
+			// do not enable JBR decorations if frame is undecorated
+			if( frame.isUndecorated() )
+				return;
+
+			// enable JBR custom window decoration for window
+			setHasCustomDecoration( frame );
+
+			// enable Swing window decoration
+			frame.getRootPane().setWindowDecorationStyle( JRootPane.FRAME );
+
+		} else if( window instanceof JDialog ) {
+			JDialog dialog = (JDialog) window;
+
+			// do not enable JBR decorations if JDialog should use system window decorations
+			if( !JDialog.isDefaultLookAndFeelDecorated() )
+				return;
+
+			// do not enable JBR decorations if dialog is undecorated
+			if( dialog.isUndecorated() )
+				return;
+
+			// enable JBR custom window decoration for window
+			setHasCustomDecoration( dialog );
+
+			// enable Swing window decoration
+			dialog.getRootPane().setWindowDecorationStyle( JRootPane.PLAIN_DIALOG );
+		}
+	}
+
 	static boolean hasCustomDecoration( Window window ) {
 		if( !isSupported() )
 			return false;