"Use of uninitialized value in numeric ne (!=) at ...Text.pm line 1223"

Well, something must be going wrong in Text.pm on line 1223. Can't say what, you provide too little information. What version of Tk? What platform? Just posting the sub the barfing line is in (and marking the line) would also help.

I couldn't reproduce that with my 'widget' and 'widget_lib'-collection (perl-Tk-804.028; perl5.8.8; Fedora7).