Using OSX 10.3.2, I've noticed this in 1094 and now in 1131. Not sure what causes it though.
I'll be editing a file, then change focus to a different app. I switch back to Idea and the cursor goes into a different 'mode'. Normally I don't allow placing of the cursor inside tabs, or after EOL. When I enter this 'mode' I can do both, and I can also highlight a square of X chars * Y chars by holding the shift key and moving the left arrow X times and the down arrow Y times. Doing the same thing in normal selection should result in an area of X chars PLUS Y LINES.
Anyone know if this is a bug, or if there's some new setting I'm missing?