at 1024x600 upon expanding an inventory bag you get "stuck" in it. there is supposedly supposed to be an X or something to get back out of the bag, but i can't prove that.
To get around this, try playing Glitch in full screen mode for your browser (F11 usually works).
The 'x' would be in the bottom row of your inventory that is off-screen. It's there! :)
I've had a friend with this problem...she fixed it by dropping the bag, but this could be a dangerous proposition if someone comes along. She has to be careful with her inventory. I haven't talked to her to see if it's still an issue.