Come again? Well, I've tested around. Even set the $width in columnInsert('end', -width => $width, -text => $text); to a fix size... no luck.. And this is where it should be the problem, so to speak... but even when I did a print Dumper($mlistbox), it said width = 20... I'm having hard time figuring what the problem could be at this point... can't be that the widget needs an update, and as seen, no wrong value... using latest Tk, v804.027...