the easiest short-term solution would be commenting out the line
menu_fixwindowmenu [lindex $i 1]
in proc pdtk_fixwindowmenu of pd.tk. This line's task is duplicated with canvas menu -postcommand, anyway, so it is not necessary.
If you do not want to mess with pd.tk, the pdtk_fixwindowmenu may be redefined using tot (still a short-term solution).
thanks ... i'll try that ...
A permanent solution: another message to canvas ('hidemenu'?).
that sounds pretty good, but i won't have the time to look into it for the next few weeks ...
cheers ... tim