added support for item attributes in virtual list control

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@10972 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/msw/listctrl.h

@@ -373,6 +373,9 @@ protected:
     // return the icon for the given item
     virtual int OnGetItemImage(long item) const;
 
+    // return the attribute for the item (may return NULL if none)
+    virtual wxListItemAttr *OnGetItemAttr(long item) const;
+
 private:
     bool DoCreateControl(int x, int y, int w, int h);