Is there a convention for the shortcut keys for application exit?
Some applications uses Alt+X some others use Ctrl+ X and Ctrl+Q.
Applications like FF and IE doesnot assign a shortcut at all.
So is there any accepted convention for that?
Note:Am talking about Windows here.
I'd say that of your three suggestions, I'd stay away from Alt+X, since that would often refer to whichever menu had X as its accelerator key, and Ctrl+X because that's usually Cut. Beyond that... I don't know.
Microsoft apps don't seem to define one, probably because you can just Alt+F4 out.
Here's a list of supported shortcuts...
http://www.computerhope.com/shortcut/windows.htm
It appears that Alt+F4 or Ctrl+F4 are your best bet. Also, Ctrl+W closes the current window in IE but also works for Explorer and other Windows windows. :)