Move wxTopLevelWindow::SetShape() down to wxNonOwnedWindow.

Also add wxNonOwnedWindow for wxMSW (which previously simply typedef'd it to
wxWindow) and document this class now that it provides some user-visible
functionality.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@69364 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/toplevel.h

@@ -219,11 +219,6 @@ public:
     // enable/disable close button [x]
     virtual bool EnableCloseButton(bool WXUNUSED(enable) ) { return false; }
 
-    // Set the shape of the window to the given region.
-    // Returns true if the platform supports this feature (and the
-    // operation is successful.)
-    virtual bool SetShape(const wxRegion& WXUNUSED(region)) { return false; }
-
     // Attracts the users attention to this window if the application is
     // inactive (should be called when a background event occurs)
     virtual void RequestUserAttention(int flags = wxUSER_ATTENTION_INFO);