Originally Posted by addressee
Anyways, here goes, reviewing ~9,000 tags ...
I can confirm that no tag appears to be causing this window/pane behaviour. Unless some tag is filled with spaces to some unknown length, I can only observe that visually, the longest title is in the range of: "Hallucinogenic Drugs - Research - Massachusetts - Cambridge - History - 20th Century" - not nearly the width of the Tag Browser pane. (screen capture attached)