MyGUI[3.0.1]: EventHandle_WidgetVoid does not define += op

Hi Guys,

I'm trying to use MyGUI for a project and on compilation it complains:
error C2676: binary '+=' : 'MyGUI::EventHandle_WidgetVoid' does not define this operator or a conversion to a type acceptable to the predefined operator

This was coded by someone to list to mouse-click events of a widget. It looks something like this:
widget->eventMouseButtonClick += newDelegate(this, &MyGUISystem::widgetClicked);

Does anyone know how to acheive the same in version 3.0.1?

Use '=' instead of '+=' in older versions of MyGUI.