cocoa doesn't need system framework - string conversion for cocoa - focus for cocoa - a bit of change for string unit tests for new functionality

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@29780 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/cocoa/window.h

@@ -81,6 +81,7 @@ protected:
 
     void CocoaCreateNSScrollView();
     void InitMouseEvent(wxMouseEvent &event, WX_NSEvent cocoaEvent);
+    virtual wxWindow* GetWxWindow() const;
     virtual void Cocoa_FrameChanged(void);
     virtual bool Cocoa_drawRect(const NSRect &rect);
     virtual bool Cocoa_mouseDown(WX_NSEvent theEvent);