A sample of a layer that causes the problem. overflow is set to auto.
Move the pointer up to the "links"-button to activate the hidden layer and then move it down towards this layer.
It seems there is a bug in Mozilla/Firefox in handling a layer that is shown/hidden through JavaScript. I wanted to have a text-container to stay in its defined size and show scrollbars if necessary plus an overlaying hidden layer for the menu. It works well with IE. I haven't tested Opera and Safari so far...
The underlaying layer has one of the following parameters that cause the bug:
overflow:auto or scroll
They cause the overlaying layer to disappear when reaching the border of the scrollable layer with the mouse pointer.
It works with:
overflow: none , inherit and visible
For suggestions and hints mail to stefan.jaeger@gmx.net
Johannes Lugmayr found a workaround for that bug. The solution is, to wrap an additional layer around the buggy one and set the z-index correctly. The workaround-layer also has to be set to overflow: auto
A working test page can be found here. Have a look at the source code.