I am not sure I like this logic of preventing all keyboard presses that come in. I know the SDL input library does the same, and it has the effect that shortcuts like `F5 Refresh` and `Alt+F4 Close` will stop from working, but also one cannot then type into text fields or other controls on the page, if it has any. In new Firefox Nightly that has the Australis theme, the menu bar is toggled via pressing `Alt`, and this preventDefault(); will stop the user from being able to bring that up. Although I'm not quite sure what would be a good way around these at the moment.