This error occurred in 1.4, so I have no idea if it is of any use to you, but I thought I’d report it anyway.
After unclicking the ‘fix capitalization of sentences’ box in the Options menu and returning to the text editor, a long, flashing black line appeared. The line started at the cursor and continued all the way to the end of the line I was working on. The line didn’t seem to affect my ability to edit the text, but it was really annoying. I shut the program down and restarted it, but the line remained. It went away when I went back into options and turned ‘fix capitalization’ back on. The line did not come back when I went back into options a third time and turned ‘fix capitalization’ off again.
I’m not sure if you need to know this, but when I was in the options menu the first time (before the line appeared), I clicked through all of the tabbed options. The only things I actually clicked on were the Nietzshe quote in the ‘Editor’ tab (which highlighted the quote, but I didn’t attempt to alter it) and the ‘Ruler snap after every…,’ also in the ‘Editor’ tab. On the ‘ruler snap,’ I accidentally raised the snap from ‘no snap’ to 0.125", but I immediately fixed it. The only change I saved was the ‘fix capitalization’ discussed above.