I checked the z-index, but the z-dialog index is higher than the overlay div. That should be right.
It works correctly in the window.
Could you help me with this problem?
Set appendToBody = true and your problem will disappear, but be careful to have an internal form if you are doing server-side processing. More info when you post more info!
appendToBody = true
For 5.1 performances you can use appendTo = "@ (body)"