hmm... I'm not sure about the right solution for your problem, but the perl-gtk guide says:

There are also two convenience functions that should be used when a lot of changes have to be made to the list. This is to prevent the list flickering while being repeatedly updated, which may be highly annoying to the user. So instead it is a good idea to freeze the list, do the updates to it, and finally thaw it which causes the list to be updated on the screen.

$clist->freeze();
$clist->thaw();

Maybe you should try these functions instead.

MP