I've never had to use Tkx so I had a Google about and got rather confused as there appear mentions of modules named with the same letters but different cases; Tktable, TkTable, tkTable and tktable. Are they perhaps all versions of the same basic module or are they reinventions of the same wheel?

Your mention of ActiveState and your code implies that you are using this. No longer (not for years) having any ActiveState instance installed, I can't check in the documentation. Looking at the package details (browse to a particular architecture version) suggests that it is derived from this and again I could find no documentation.

The only useful documentation I could discover was this but in it I could see no method that would allow sizing of individual columns, all column-specific methods seem to apply globally. I hope the references I've found will help you to investigate further and find something more useful.