Ext.ux.maximgb.tg.GridView = Ext.extend(Ext.grid.GridView, 
{   
    expanded_icon_class : 'ux-maximgb-tg-elbow-minus',
    last_expanded_icon_class : 'ux-maximgb-tg-elbow-end-minus',
    collapsed_icon_class : 'ux-maximgb-tg-elbow-plus',