@Override
		public void propertyChange( PropertyChangeEvent e ) {
			switch( e.getPropertyName() ) {
				case JInternalFrame.TITLE_PROPERTY:
					titleLabel.setText( frame.getTitle() );
					break;

				case JInternalFrame.FRAME_ICON_PROPERTY:
					updateFrameIcon();
					break;

				case JInternalFrame.IS_SELECTED_PROPERTY:
					updateColors();
					break;

				case "iconable":
				case "maximizable":
				case "closable":
					updateButtonsVisibility();
					enableActions();
					revalidate();
					repaint();

					// do not invoke super.propertyChange() because this adds/removes the buttons
					return;

				case "componentOrientation":
					applyComponentOrientation( frame.getComponentOrientation() );
					break;

				case "opaque":
					// Do not invoke super.propertyChange() here because it always
					// invokes repaint(), which would cause endless repainting.
					// The opaque flag is temporary changed in FlatUIUtils.hasOpaqueBeenExplicitlySet(),
					// invoked from FlatInternalFrameUI.update().
					return;
			}

			super.propertyChange( e );
		}
Does nothing because FlatLaf internal frames do not have system menus.
flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatInternalFrameTitlePane.java