MarsEdit locks up when selecting last category item

I do need to submit this as a bug report or support request, but I’m noticing all the hits I’m getting for talking about MarsEdit and Drupal … so I’m just going to mention this here, first. I’m getting lockups in MarsEdit — both the last Newsgator edition and the new version just released by Red Sweater Software — when I select the last category item in the drawer for a blog post.

Initially, I get a spinning beach ball cursor. Then, MarsEdit stops responding to many kinds of input. I can still bring the application to the front, and for a few moments, I may be able to bring the “MarsEdit” window to the foreground, but eventually, all I can do is drag that window. The blog post editing window I was working on disappears; I can’t even see it when using Exposé’s all-window mode.

If I attempt to quit MarsEdit — which I have to do from its Dock icon — I do get prompted to save the new/modified post. However, the Save sheet drops down from an invisible window, which is very odd. If I click the mouse cursor in the screen area around that sheet, I do get to see the window. I can click in the buttons in the dialog sheet but nothing happens.

After a Force Quit, I have been prompted that an auto-save version of the post is available. I can resume from that point.

This lockup happens for me specifically in my Drupal stories blog in MarsEdit (which is configured as a Movable Type API blog). I have quite a few categories (30ish?) listed there from my Drupal taxonomy. I haven’t tried adding a term that is alphabetically later than the current one, to see if it’s something about the category/term, or the position, or what.

For what it’s worth, some of those taxonomy terms are duplicated in the list in MarsEdit.

I wonder if anyone else is seeing this kind of behavior.