Every application, especially gnome based applications are having this option in menu, so I think it would be good to have it, I am not sure if there is a special reason that particularly this one application does not contain this option
*** Bug 1255337 has been marked as a duplicate of this bug. ***
Still no Quit button. On top of this not even a Ctrl+Q shortcut is set for this application. This issue makes quitting quite troublesome with automated tests (not impossible). Are there any plans regarding this bug?