Reworked wxPGCell. It is now reference counted, and therefore much more user friendly, and is used internally as basis for most property colour values instead of separate row text and bg colours.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@56622 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

samples/propgrid/propgrid.h

@@ -179,6 +179,7 @@ public:
 
     void OnEnableDisable( wxCommandEvent& event );
     void OnHideShow( wxCommandEvent& event );
+    void OnSetBackgroundColour( wxCommandEvent& event );
     void OnClearModifyStatusClick( wxCommandEvent& event );
     void OnFreezeClick( wxCommandEvent& event );
     void OnDumpList( wxCommandEvent& event );