Added a virtual wxWindow::OSXGetViewOrWindow() method.

This can be used to retrieve either an NSView for child windows or NSWindow
for non-owned ones without resorting to dynamic casts.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@62303 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/osx/nonownedwnd.h

@@ -97,6 +97,11 @@ public:
 
     wxNonOwnedWindowImpl* GetNonOwnedPeer() const { return m_nowpeer; }
 
+#if wxOSX_USE_COCOA_OR_IPHONE
+    // override the base class method to return an NSWindow instead of NSView
+    virtual void *OSXGetViewOrWindow() const { return GetWXWindow(); }
+#endif // Cocoa
+
     // osx specific event handling common for all osx-ports
 
     virtual void HandleActivated( double timestampsec, bool didActivate );