Hi, This is most likely because FVWM thinks the window displaying the PNG file with alpha transparency is a shaped window.
Vincent, can you confirm this for me, by recompiling FVWM without shape support? If this turns out to work for your mutt icon test case, I'll fix this upstream by introducing a BugOpts option. This was very easy for me to track down, FWIW. -- Thomas Adam -- "It was the cruelest game I've ever played and it's played inside my head." -- "Hush The Warmth", Gorky's Zygotic Mynci. -- To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org