On 2020-10-12 7:45 am, Eli Zaretskii wrote:
>> Date: Sun, 11 Oct 2020 20:25:13 -0700
>> From: Jared Finder <jared@finder.org>
>> Cc: emacs-devel@gnu.org
>> 
>> -(defun menu-bar-open-mouse (event)
>> +(defun menu-bar-open-mouse (position)
>>    "Open the menu bar for the menu item clicked on by the mouse.
>> -EVENT should be a mouse down or click event.
>> +POSITION should be a list of the form returned by `mouse-position'.
>> 
>>  Also see `menu-bar-open', which this calls.
>>  This command is to be used when you click the mouse in the menubar."
>> -  (interactive "e")
>> -  (let* ((x-position (car (posn-x-y (event-start event))))
>> +  (interactive (list (mouse-position)))
>> +  (let* ((x-position (cadr position))
> 
> I'd prefer not to lose the "e" interactive spec and the form of the
> argument here.  If the problem is the conversion of window-relative to
> frame-relative coordinates, that is easy, and the ELisp manual has an
> example of how to do that in the node "Accessing Mouse".
> 
> Or is there some problem to use this here?

Thanks, I investigated further and I have an improved patch attached.  
In addition to keeping the same interactive spec, it also is logically 
independent of my changes to enable xterm-mouse based menu interaction.  
I also attached repro.el, which I used to help understand the behavior 
of xterm-mouse.

The manual is not clear of the format of a posn for clicks outside a 
window, such as on the menu bar or tab bar. From the behavior I see, 
posn-window will return nil and posn-x-y will return (x . y) in frame 
coordinates. I rely on that in this patch. If this is accurate, I can 
update the manual.

   -- MJF