I had envisioned various possibilities for what might happen on Windows, but cut-off toolbar buttons was not one of them. I also didn’t understand the toolbar layout code. I had written a toolbar manager before and didn’t want to volunteer any of my life on that boring problem.
However, I felt bad and that I should at least put some effort into trying to fix the problem. So that evening, I decided to just read through the toolbar code from beginning to end and see if I found anything obviously wrong. You don’t have to be very clever to notice a bloody knife at a murder scene.