The unbinding order in x_consider_frame_title is botched.  Hence,
while do_switch_frame will not resize the minibuffer window when the
frame of the title bar gets selected, it will still resize when the
old frame gets reselected in the unbind form.

The behavior can be seen with emacs -Q evaluating the following two
forms in row:

(make-frame '((minibuffer . nil)))
(y-or-n-p "\n")

The attached trivial patch cures it.  Obviously, there's no guarantee
that some other client relies on the wrong order.

martin