On Thu, Nov 2, 2017 at 5:51 AM, martin rudalics <rudalics@gmx.at> wrote:

>
> ‘frame-x-dot-y’ should be the Emacs frame under the mouse which is not
> necessarily the selected frame.  Why do you want it to be the selected
> ​​
> frame?  Don't you want to drop your object on the frame under the mouse?

​​
​I see your point and agree.
​​
​But this is not what mouse-position and ​pixel-position return by default
(when mouse-position-function is nil)
on MacOS.  They always return the last registered frame which is the frame
that was last clicked upon twice (as you
have noted, a single click does not register with Emacs but only selects
the frame).  This seemed to be the case under
Windows 7 for me as well, using Emacs -q under Emacs 25.3 and Emacs 26.

Since I always reference the mouse position after a click or drag and can
make the new frame be selected after a drag,
I wrote the function this way to give me the most recently selected frame.

There needs to be a fix in the core of Emacs so these functions can return
the frame under the mouse regardless of how
the window manager handles selecting frames, I think.

Bob