Covering Flash with HTML Elements
Several teams have Flash content on their site that needs to be hidden by popup menus or tabs.
It is a known problem that, regardless of z-index, Flash covers HTML content.
Why Flash Covers HTML
Flash gets its own hWnd in Windows and, although it appears to be in the browser window, it actually draws
independently of the HTML rendering surface.
In this mode, there is no way for the browser to show anything overtop the Flash container.
How to Hide Flash
The solution is to add the “wmode=opaque” parameter to every Flash and element:
...
In “opaque” mode, the browser tells Flash when to draw on the HTML rendering surface.
This is slower than when Flash has its own hWnd, but it is the only way to layer HTML elements overtop Flash.
Although “wmode=transparent” also works, this involves calculating transparency and is slower.
Avoid this performance hit unless you need to show HTML through the “holes” in a Flash movie.
Test Pages
This test page shows the effect of “wmode=opaque”:
http://livetech/20070927-talk/flash-zindex/
More Information
Some background on this issue:
http://www.adobe.com/cfusion/knowledgebase/index.cfm?id=tn_15523
Directly from Adobe; they recommend using “wmode=opaque” or “wmode=transparent”
http://www.communitymx.com/content/article.cfm?cid=E5141
A good article with demo pages