TextMate: shape of caret suddenly changed from rectangle to underline

The shape of the caret suddenly changed from a rectangle to a very thin underline shape. The same goes for highlighting the current line. It used to be that the whole line was highlighted, now the current line is just underlined (very thinly). I can't find a setting that might have done that (I'm using latest version of TextMate, 1.5.10, on 10.6.6). It changed when I was opening a compiled PDF document in skim via control-option-command o. Any ideas on how to change 开发者_如何学Cit back?

Apologies for posting... I found out what it was. I was accidentally editing in overwrite mode, which changes the shape of the caret and line highlighting.