Dear Klaus,
This seems to be an issue with the window decorations. When FVWM wants to place
the window at certain coordinates, it takes frame and title bar into account,
but the application seems to ignore this. If it happens only with psi+, this
obviously has a bug. Tell the developers, according to my experience they are
willing to help.
I have no simple answer how to circumvent this in FVWM, especially for one
specific program only. You may try to catch the placement event in FvwmEvent.
Best regards
Werner