The scenario is all too common: An application brings up a dialog box while you are typing, and you hit the space key before you even realize what's happening. The dialog is gone and you have no clue what it said.
This is a fundamental problem with dialog box design. How do we solve it?
One possibility: Firefox brings up a confirmation dialog when installing add-ons but disables the OK button for 3 seconds. This prevents accidental confirmation (and forces you to read the warning), but in general I don't think it's a good idea to force the user to wait.