Custom Line Number Width

We're using SyntaxEditor to also be an output control for a global find feature. We are putting the file/line number of each result into the custom line number field, which works great (and meets another feature goal I don't need to mention here). Anyway, the problem is... is there a way to make the line number region auto-size? There's no way to tell how big we need to make it... filenames can vary a lot.

-- David

ps. The documentaiton seems to be missing most stuff related to locations now. You just get This Page cannot be displayed in the help. Like try and click on "LocationToPosition" in the "Offset, Positions, and Locations" page. We actually need to do LocationToPosition... is that still supported?