Fixed bug: Settings property attribute to wxNullVariant would cause GetAttribute() to fail (wxPG SourceForge bug #2128485)

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@55870 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

interface/wx/propgrid/property.h

@@ -1144,6 +1144,9 @@ public:
 
         @param value
             Value of attribute.
+
+        @remarks Setting attribute's value to Null variant will simply remove it
+                from property's set of attributes.
     */
     void SetAttribute( const wxString& name, wxVariant value );