GameObject disappear from Clipping ? How check it?

[PoN]

Who could help me, i want to check gameobject which go out from a clip area in Panel with Clipping (determine a gameobject is disappear from Clip area)? now i have decision ,that is calculate the Y position of gameobject by

1.  yPos = NGUIMath.CalculateRelativeWidgetBounds (_transform_of_clip_panel, item.gameobject.transform).center.y+deltaY;

then checking with Y bounds of clip area  in Update() . Maybe have a better way ?
thanks

[ArenMook]

UIWidget.isVisible tells you whether it's visible or not. You don't need any bounds checks.