* Viktor Griph | Look att UrgencyFunc in the manpage. It might be that firefox | (incorrectly) use the urgency hint when a new tab is opened. In | that case Destroying UrgencyFunc should stop the behavior, but you | might want to redefine it in some other way to maybe just ignore | firefox.
Thanks for the pointer. I have added to my ~/.fvwm2rc ### firefox tab popup DestroyFunc UrgencyFunc but this does not change anything. I also added AddToFunc UrgencyFunc + I Exec xterm + I Echo UrgencyFunc to see whether this function was called at all, but no xterm appears, and no message is printed when the desktop is switched. So this is probably not what happens here... I had hoped that fvwm2 --debug would print something, but it does not... R'