On occasion, when I click on a window (by tapping on the trackpad), the window goes into some strange movement mode - keyboard input is ignored, and wherever I click next the window is moved to (and strange mode reverted).
I can't find anything in preferences that relates to this. I'd rather have it turned off completely, but I'd settle for knowing how I'm accidentally doing it, so I can avoid doing so.
This is on 10.6.8.