bug#21348: 25.0.50; Screen scaling factor >=2 causes menus, tooltips to display in the wrong place

[Eli Zaretskii]

> Date: Wed, 26 Aug 2015 10:56:32 +0200
> From: martin rudalics <rudalics@gmx.at>
> CC: 21348@debbugs.gnu.org
> 
>  >> I'm on Ubuntu 14.04.3 using a Dell XPS 13, which has screen resolution
>  >> 3200x1800. In order to make the menus large enough to read, the screen
>  >> is scaled at x2.
>  >
>  > What does that mean?  Which pixel coordinates are affected by this,
>  > and how could Emacs know that?
> 
> Via gtk_widget_get_scale_factor, I suppose.

But if GTK knows about that, shouldn't it DTRT with tooltips
automagically?  In a GTK build the tooltips are presented by GTK,
right?