Az Mwm dekoráció egyébként nekem sem megy.
Azért helyes a bugleírása: :-)):

BUGS

This is a Tix extension which perl/Tk has adopted. It has not been tested as perl/Tk's author has not got round to installing a Motif Window Manager.

On some versions of mwm, the -border will not disappear unless -resizeh is turned off. Also, the -title will not disappear unless all of -title, -menu, -maximize and -minimize are turned off.

:-)