Remove wxGTK1 mentions from the documentation

GTK1 is no longer supported, so do not document control limitations when using it.

interface/wx/window.h

@@ -2196,10 +2196,10 @@ public:
     virtual bool HasTransparentBackground();
 
     /**
-        Causes this window, and all of its children recursively (except under wxGTK1
-        where this is not implemented), to be repainted. Note that repainting doesn't
-        happen immediately but only during the next event loop iteration, if you need
-        to update the window immediately you should use Update() instead.
+        Causes this window, and all of its children recursively, to be repainted.
+        Note that repainting doesn't happen immediately but only during the next
+        event loop iteration, if you need to update the window immediately you
+        should use Update() instead.
 
         @param eraseBackground
             If @true, the background will be erased.