I found this in the Mozilla Wiki on the change: http://wiki.mozilla.org/Ctrl_W_not_close_app
> Proposed change > > Ctrl+w should behave as the tab bar's close button already does, and as > Ctrl+F4 already does, and as right click on tab -> "Close tab" already > does. Ctrl+W and File->Close Tab should be consistent with every other > tab-closing method, and close the tab, but not the window. >
