Detecting minimisation state changes in OSX.

modules/juce_gui_basics/native/juce_mac_NSViewComponentPeer.mm

@@ -81,11 +81,23 @@ public:
                                   object: view];
 
         if (! isSharedWindow)
+        {
             [notificationCenter  addObserver: view
                                     selector: @selector (frameChanged:)
                                         name: NSWindowDidMoveNotification
                                       object: window];
 
+            [notificationCenter  addObserver: view
+                                    selector: @selector (frameChanged:)
+                                        name: NSWindowDidMiniaturizeNotification
+                                      object: window];
+
+            [notificationCenter  addObserver: view
+                                    selector: @selector (frameChanged:)
+                                        name: NSWindowDidDeminiaturizeNotification
+                                      object: window];
+        }
+
         [view setPostsFrameChangedNotifications: YES];
 
         if (isSharedWindow)