Emacs Tip #36: Abort the minibuffer when using the mouse

A friend of mine loves using Emacs, but is always complaining about something. This time it's Emacs' behavior to keep the minibuffer active when you use the mouse to select another window. For example, you start doing a C-x C-f, click elsewhere, and do the C-x C-f again. Emacs will beep and tell you Command attempted to use minibuffer while in minibuffer.

After swallowing my, "well don't use the mouse" response I set about trying to fix it. I'm sure this has been solved before, I just didn't have enough google-fu to find the solution.

(defun stop-using-minibuffer ()
  "kill the minibuffer"
  (when (and (>= (recursion-depth) 1) (active-minibuffer-window))
    (abort-recursive-edit)))

(add-hook 'mouse-leave-buffer-hook 'stop-using-minibuffer)

Edited to add:
A commenter suggested using recursive minibuffers. I think that the resulting behavior is more confusing than helpful.

Yes, it avoids the error, but then you get this ever-increasing stack of minibuffers building up. If/when the user notices the minibuffer hanging around it'll be annoying (I've had people ask, "Why is it trying to find a file?" (because the minibuffer still shows Find file: /path/to/somewhere)). And heaven forbid they click in the minibuffer, type C-g and get back to the window configuration they were looking at when they started that command, which was ... 15 minutes ago.