I posted about this issue on the fvwm forum at fvwm.lair.be and got
I would like to auto-iconify windows that are not visible on the
screen anymore (i.e. the got totally overlapped by other windows).
However the following code, does not work when xcompmgr is running at
the same time:
All (CurrentPage, !Visible) Iconify True
I have also tried running xcompmgr with different arguments, but with
The "Visible" condition works perfectly if xcompmgr is not running
though. I do not know if it is FVWM or xcompmgr that is at fault.
I use fvwm 2.5.21 (with support for: ReadLine, Stroke, XPM, PNG,
Shape, XShm, SM, Bidi text, Xinerama, XRender, XFT, NLS), xorg-server