bug#47969: 28.0.50; Losing minibuffer focus in trying M-x command

[Gregory Heytings]

> > Patch attached.  Could you please test it, and confirm that it 
> > correctly fixes the issue?
> >
> > Cc'ing Martin, who authored most of the handle-select-window function. 
> > The recipe is upthread.
>
> I don't know what to say because (1) moving the mouse to the lower 
> window does _not_ lead to typing "gnus" in that window here and

Are you sure?  I tried this recipe on GNU/Linux (27.2 and 28), macOS 
(27.2) and Windows (27.2), and in all cases "gnus" was typed in that 
window.  Note that the recipe uses ESC x, not M-x.

> (2) I'd rather consider it a bug to _not_ select the lower window in 
> that case.

I don't know.  What I do know is that mouse-autoselect-window was 
introduced in Emacs 22, and that in Emacs 22-25 the lower window was not 
selected with that recipe.  That behavior changed in Emacs 26.

> Mouse window auto-selection should mimic the behavior of clicking into 
> the lower window and clicking in that window should select it also while 
> a minibuffer dialogue goes on.

This is not the case, not even in Emacs 28.  If it were the case, the 
"ESC" would be discarded and "xgnus" would be typed in the lower window. 
What happens is that "x" becomes "M-x" because of the earlier "ESC", "M-x" 
stays in the minibuffer, and "gnus" in typed in the buffer.