GtkWidget::intersect
GdkRectangle
      intersect
     (
      GdkRectangle
      area
     ); 
    
     intersect()  returns the rectangle
     consisting of the overlap of the area taken up by the calling widget and
     area. This method could be useful to determine if
     a use is trying to drag and drop a widget some where that they shouldn't.
    
    
     If the two areas do not intersect false is return.