Implemented desktop manager wrapper for already installed desktop manager so the iconifyFrame with small

content snapshot are still available

Signed-off-by: Stephan Bodmer <sbodmer@lsi-media.ch>

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

@@ -47,6 +47,7 @@ public class FlatDesktopPaneUI
 		if (old instanceof FlatDesktopManager) return;
 
 		if( old == null ) {
+			// default version
 			desktopManager = new FlatDesktopManager();
 
 		} else {