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DHTML vs. plugins, forms, and iFrames

One of the most common mistakes inexperienced site designers and developers can make is to assume that browsers act consistently. Sadly, they don't. Not at all. Not even close.

One particularly vexing issue is exposed when sites employ DHTML such as drop-down menus, only to find that when their menus fall over certain page elements, like form widgets, plugins, and iframes, different and unexpected things happen. Part of an in-page element might blast through the DHTML menu, or the menu may fall behind the element. Not surprisingly (to veterans, anyway) the behavior is different across browser versions and platforms.

Unfortunately, there is no fix. The best you can do is educate your team so that DHTML enhanced designs won't trip over this issue. Web Reference has published an exhaustive review of the problem in an article entitled Positioned Elements and OS Controls, Applets and Plug-ins, and is just the ticket: bookmark it, read it, send it to all your friends.