Added wxPGProperty::OnValidationFailure(); needed it and some other tweaks to allow vetoing value changes of ComboBox editors

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@58047 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/propgrid/propgrid.h

@@ -1294,12 +1294,8 @@ public:
         To add your own validation failure behavior, override
         wxPropertyGrid::DoOnValidationFailure().
     */
-    bool OnValidationFailure( wxPGProperty* property, wxVariant& invalidValue )
-    {
-        bool res = DoOnValidationFailure(property, invalidValue);
-        property->SetFlag(wxPG_PROP_INVALID_VALUE);
-        return res;
-    }
+    bool OnValidationFailure( wxPGProperty* property,
+                              wxVariant& invalidValue );
 
     /** Called to indicate property and editor has valid value now.
     */