A Tricky Level of HTML Tag

This illustration is a level of HTML tag when you wanna manipulate them between each other to show the correct layout. Especially in IE6, when you develop a drag-drop Javascript code, you should find that the overlapped Div is placed under the Select tag (a drop-down list), even using the z-index CSS. Fortunately, the issue is only caused by IE6, and a solution is appeared that the Iframe tag is higher than the Select tag so we can use a empty Iframe to apply to the Select, then use the overlaped Div over the Iframe to resolve this issue. This way can also cope with a dragging event lost, when the action is over the Iframe.