Solve the control occlusion problem: there are window elements and no window elements. I don't know if my friends have encountered the control occlusion problem. The most typical issue is DropdownList and ActiveX occlusion. the z-index of HTML is used to solve this problem, however, if you directly set this parameter, you do not know whether your friends have encountered the control occlusion problem. The most typical issue is DropdownList and ActiveX occlusion. The HTML z-index is used to solve this problem, however, setting this attribute directly does not work, because it also involves the problem of having window elements and having no window elements.
Window elements include the following types:
ActiveX control, Plug-ins, DHTML Scriptlets, SELECT elements (HTML representation of DropdownList), IFRAMEs before IE5.01
Windowless elements include:
Windowless ActiveX controls, IFRAMEs after IE5.5, and most DHTML elements
Among them, ActiveX controls are worth mentioning. by default, VB and MFC controls have windows, while ATL controls do not, however, ActiveX controls are implemented as windowless elements and are actually classified into windowless elements.
No matter how the container is set, all window elements will appear on the element without a window, and the elements with and without a window will follow the z-index attribute, they will be drawn on different planes for display. setting z-index can only work on the plane where they are located, and the plane with window elements is always above the plane without window elements.
The idea of solving the occlusion problem is very simple. We encapsulate our elements into a DIV, and the code example is as follows:
DIV's z-index is 8, and then the SELECT z-index is adjusted to 7 (only smaller than DIV's z-index ).
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