Ctrl W not close app

Discuss: Ctrl-W on last tab should not close firefox. Ref: bug in bugzilla.

Use case

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.

In detail:

• Ctrl+W will close the selected tab, as per currently, until only one tab is left.
• When that tab is left, ctrl+w will blank the tab and clear session history (basically a quicker way of closing the tab and creating a new one).
• If Ctrl+W is pressed again, treat as above - i.e. you still have the window open, with one blank tab, with no session history.

Arguments in favour and against

Pro

• Inconsistency: Close tab button and Ctrl-W are currently inconsistent ("close tab button" keeps app open, ctrl-W closes the (possibly last) window). Also in the same way, currently inconsistent with right click on tab -> "Close tab" (which cannot close the app).
• There's already a keyboard shortcut for closing the window (SHIFT+CTRL+W).
• Surprise: The current behaviour is often surprising - "Whoa! Where did my browser window just go?". New behaviour will not be surprising to the new user in this way.
• It's currently in an extension (Tab Mix Plus, under "Events" tab -> option "Do not close window when closing last tab by hotkey"), so there is demand for this and it can be done on Firefox.
• Non-intrusive: There was a patch (now out of date) which nevertheless showed how to do this, and the changes required were small (2 Kb).
• Precedent in other multi-tabbed browsers: This is how tab closing via Ctrl-W works in IE7, NetCaptor, and Opera, among others.
• Clarity: Closing the tab and closing the window are two very different things - one means "I'm done with the current block of information, but this app is still useful to me", and the other means "this entire app is no longer of any use to me" - they are conceptually different things. At the moment this is being muddied by having the meaning of Ctrl-W change between these two things, depending on context.
• Faster: Can close all tabs by holding down ctrl-W for 1 second, which is faster than switching to the mouse.

Con

• It's a change in the User Interface from how it was in Firefox 1.0 and 1.5.
• Closing a tab that creates a new blank tab is arguably not closing a tab.
• Users on UNIX systems wanting mouse keyboard bindings may want a key binding that uses two keys rather than 3 to close the window (although Alt-F4 may do this?)
• There's already a keyboard shortcut for closing the tab, if not the last one (ctrl-F4)
• Firefox supports multiwindow tabless browsing; ctrl-w not closing the window along with its directly contained document is inconsistent with IE6 and other tabless applications