[Development] Wayland: getting a screen's fractional scale before the first window exists

[David Edmundson]

On Fri, Aug 7, 2026 at 11:35 PM Jamie Fitzgerald via Development
<development at qt-project.org> wrote:
>
> Hi all,
>
> I work on the Qt/Wayland side of LibreOffice's VCL plugin, and I'd like to ask whether Qt could expose a screen's fractional scale before any window exists, and if so, what shape you'd want it in.
>
> Why it's needed: LibreOffice sizes its menus, toolbars and dialogs while starting up, before it opens its first window.

There's two relevant problems at play here.

 1) The window doesn't know the proper scale until the surface is
configured by the compositor
 2) The window doesn't know what screen we're on until the surface is
configured by the compositor

Even if we came up with a workaround to point 1, we haven't solved
point 2 and we ultimately haven't accomplished anything.
Either clients wait for the expose event before rendering/follow DPR
changes or things are still broken.

I know libreoffice has a GTK backend, they'll be faced with the same
constraints. Do they do anything differently?

David