Comment 44 for bug 1500282

(In reply to Stefan Seidel from comment #37)
> (In reply to Felix Miata from comment #36)
> > To be clear, Xft.dpi is not the only means to scaling in Xorg. On my many
> > Linux installations, few of which ever run at 96 DPI, and none of which
> > include Gnome, Xft.dpi is always null. Here, DPI is always forced otherwise
> > either via xrandr, or DisplaySize.
>
> I have yet to find an application that scales according to the xrandr/Xorg
> DPI value. Maybe it is my setup but I have tried for years and I've never
> seen an application using this DPI value.

Wondering the same:

Where exactly is Firefox reading the system value from so that it can automatically adjust layout.css.devPixelsPerPx when it is set to -1.0 (default value)?

And would it be possible to alter layout.css.devPixelsPerPx and/or the system value via the terminal/via a command?

Would be very much appreciated if someone could explain.

Regards