It's not a specific writer problem, it happens every time in full screen mode if 
modal dialogs starts. (Please check it also under Solaris)

This will need some redesign of the full screen mode itself. Depending on the
window manager it can be impossible to raise a managed window over an
override-redirect window.

As a temporary workaround dialogues come up override redirect if fullscreen
mode is active. At least they come up in front then. But since they are not
decorated in this case, there will have to be another solution. Making the
fullscreen mode not override redirect fails on many window managers since either
the position is incorrect or the fullscreen window gets lowered.

with EWMH compliant window managers this ceased to be a problem long ago, closing