Add a 'quit' message that is app-wide, as opposed to mir_event_type_close_surface

Just marked unity7 also affected, as its implementation is similar (it’s Bamf windows instead of Mir surfaces, but essentially it behaves the same).

And also marked unity8 affected, because the wording of the action in the context menu is confusing wrt the actual implementation: if we don’t change the actual implementation, we might want to rename "Quit" to "Close all windows".

Windows appears to have a WM_QUIT message¹ that’s used to request quitting an application, and Qt handles it correctly in QEventDispatcherWin32::processEvents(). I guess we need something similar for Mir?

¹ https://msdn.microsoft.com/en-us/library/windows/desktop/ms632641(v=vs.85).aspx

AFAICS Mir has means to ask clients to close windows, but I don't see an API to ask the client itself to quit.

AFAIK Mir follows the same model as X11 (which has the WM_DELETE_WINDOW message but no WM_QUIT). I guess you could kill(pid, SIGTERM)?

Given that, unlike X11, we have some control over Mir’s design and implementation, maybe this is something that we could consider adding? Or is that out of place?

It is not out of place at all - just an enhancement request.

Status changed to 'Confirmed' because the bug affects multiple users.

Does Mir provide enough api to allow application ask user a question before shutdown? In Unity7, typically that is requesting focus and popping up a dialog - should be ok, but good to think about it.

Clicking on a window's close button sends the app mir_event_type_close_window. That's just an informational message that apps are meant to act on (e.g. pop up a dialog if not terminate themselves).

If you mean logout however, then I guess the right answer is that shells should send mir_event_type_{close_window,quit_app} to all apps on logout, and wait until the apps are no longer running (user responds to dialogs from apps with unsaved work or some timeout expires).

Maybe a fix for bug 1674749 is what you want.

I’m not sure how a fix for bug #1674749 would address the use case in the description: a multi-window application (such as web browser) wants to distinguish between:

 - please close all windows one by one without retaining state for them

 - please quit the app, and save the state for all windows and tabs in them

Generally speaking fixing bug 1674749 (now bug 1671424) should be enough for most apps in the short term.

I'm reminded of how Microsoft handles this problem...

WM_CLOSE: https://msdn.microsoft.com/en-us/library/windows/desktop/ms632617(v=vs.85).aspx

WM_QUIT: https://msdn.microsoft.com/en-us/library/windows/desktop/ms632641(v=vs.85).aspx
"The WM_QUIT message is not associated with a window and therefore will never be received through a window's window procedure."

WM_POWERBROADCAST: https://msdn.microsoft.com/en-us/library/windows/desktop/aa373247(v=vs.85).aspx

WM_ENDSESSION: https://msdn.microsoft.com/en-us/library/windows/desktop/aa376889(v=vs.85).aspx

Each has a valid use case, and I don't think we can get away from similarly wanting a 'quit' message in Mir eventually.