diff --git a/src/osx/cocoa/nonownedwnd.mm b/src/osx/cocoa/nonownedwnd.mm
index a5eed3e9bb..9a7bb661e6 100644
--- a/src/osx/cocoa/nonownedwnd.mm
+++ b/src/osx/cocoa/nonownedwnd.mm
@@ -305,6 +305,8 @@ static NSResponder* s_formerFirstResponder = NULL;
 // controller
 //
 
+static void *EffectiveAppearanceContext = &EffectiveAppearanceContext;
+
 @interface wxNonOwnedWindowController : NSObject <NSWindowDelegate>
 {
 }
@@ -610,6 +612,32 @@ extern int wxOSXGetIdFromSelector(SEL action );
         [view setFrameSize: expectedframerect.size];
     }
 }
+ 
+- (void)addObservers:(NSWindow*)win
+{
+    [win addObserver:self forKeyPath:@"effectiveAppearance"
+             options:0 context:EffectiveAppearanceContext];
+}
+
+- (void)removeObservers:(NSWindow*)win
+{
+    [win removeObserver:self forKeyPath:@"effectiveAppearance" context:EffectiveAppearanceContext];
+}
+
+- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context
+{
+    if (context == EffectiveAppearanceContext)
+    {
+        wxNonOwnedWindowCocoaImpl* windowimpl = [(NSWindow*)object WX_implementation];
+        wxNonOwnedWindow* wxpeer = windowimpl ? windowimpl->GetWXPeer() : NULL;
+        if (wxpeer)
+        {
+            wxSysColourChangedEvent event;
+            event.SetEventObject(wxpeer);
+            wxpeer->HandleWindowEvent(event);
+        }
+    }
+}
 
 @end
 
@@ -632,6 +660,7 @@ wxNonOwnedWindowCocoaImpl::~wxNonOwnedWindowCocoaImpl()
 {
     if ( !m_wxPeer->IsNativeWindowWrapper() )
     {
+        [(wxNonOwnedWindowController*)[m_macWindow delegate] removeObservers:m_macWindow];
         [m_macWindow setDelegate:nil];
      
         // make sure we remove this first, otherwise the ref count will not lead to the 
@@ -648,6 +677,7 @@ void wxNonOwnedWindowCocoaImpl::WillBeDestroyed()
 {
     if ( !m_wxPeer->IsNativeWindowWrapper() )
     {
+        [(wxNonOwnedWindowController*)[m_macWindow delegate] removeObservers:m_macWindow];
         [m_macWindow setDelegate:nil];
     }
 }
@@ -738,6 +768,7 @@ long style, long extraStyle, const wxString& WXUNUSED(name) )
     [m_macWindow setLevel:m_macWindowLevel];
 
     [m_macWindow setDelegate:controller];
+    [controller addObservers:m_macWindow];
 
     if ( ( style & wxFRAME_SHAPED) )
     {