def draw_item(self, context, layout, data, item, icon, active_data, active_propname, index):
        # assert(isinstance(item, bpy.types.VertexGroup))
        vgroup = item
        if self.layout_type in {'DEFAULT', 'COMPACT'}:
            layout.prop(vgroup, "name", text="", emboss=False, icon_value=icon)
            icon = 'LOCKED' if vgroup.lock_weight else 'UNLOCKED'
            layout.prop(vgroup, "lock_weight", text="", icon=icon, emboss=False)
        elif self.layout_type == 'GRID':
            layout.alignment = 'CENTER'
            layout.label(text="", icon_value=icon)