bug#27053: 26.0.50; x-show-tip gets wrong mouse position if frame moves w/o mouse moving on macOS

[martin rudalics]

> Looks like the right way to get it in screen‐coords is
>
>      [NSEvent mouseLocation]
>
> which returns an NSPoint.
>
> 
https://developer.apple.com/reference/appkit/nsevent/1533380-mouselocation?language=objc
>
> Seems strange to me that it’s in NSEvent, but I guess it makes sense
> to someone.
>
> Patch attached.

I'd say go for it.

martin