Disable the opportunity to open pad settings multiple times for one pad

PlayWall/src/de/tobias/playpad/viewcontroller/pad/PadViewController.java

@@ -54,6 +54,7 @@ public class PadViewController implements EventHandler<ActionEvent>, IPadViewCon
 	private PadPositionListener padPositionListener;
 
 	private PadDragListener padDragListener;
+	private transient PadSettingsViewController padSettingsViewController;
 
 	public PadViewController() {
 		view = new PadView(this);
@@ -183,13 +184,15 @@ public class PadViewController implements EventHandler<ActionEvent>, IPadViewCon
 			}
 
 			Stage owner = mvc.getStage();
-			PadSettingsViewController controller = new PadSettingsViewController(pad, owner);
-			controller.getStage().setOnHiding(ev ->
+			if (padSettingsViewController == null) {
+				padSettingsViewController = new PadSettingsViewController(pad, owner);
+				padSettingsViewController.getStage().setOnHiding(ev ->
 				{
 					if (view != null && pad != null)
 						view.setTriggerLabelActive(pad.hasTriggerItems());
 				});
-			controller.getStage().show();
+			}
+			padSettingsViewController.getStage().show();
 		}
 	}