Re: [SOLVED] [gentoo-user] thunderbird small fonts on hidpi

[Andrew Udvare <audvare@gmail.com>]

> On 2020-06-25, at 13:40, Valmor de Almeida <val.gentoo@gmail.com> wrote:
> 
> On Thu, Jun 25, 2020 at 9:43 AM Andrew Udvare <audvare@gmail.com> wrote:
>> 
>> On 25/06/2020 04:59, Valmor de Almeida wrote:
>>> Hello,
>>> Does anyone know how to fix Thunderbird UI fonts on a HiDPI
>>> Gentoo/OpenBox system with no desktop?
>>> A similar problem exists with Firefox but it can be fixed using a CSS
>>> file (userChrome.css). However I can't get Thunderbird to work using a
>>> similar fix. The UI fonts are so small that the app is useless.
>>> Thanks,
>>> --
>>> Valmor
>>> 
>> 
>> Do you have an ~/.Xresources file? It can have something like:
>> 
>> Xft.dpi: 144
>> 
>> Which is also passed to Xorg for me: -dpi 144 (Plasma does this by
>> modifying SDDM service file(s) to systemd).
>> 
> 
> No I don't have it. I thought the line
> 
> xrandr --dpi 192 &
> or
> xrandr --output eDP-1 --mode "3840x2160" --scale "0.75x0.75"
> 
> in ~/.xinitrc was sufficient to fix Firefox; it doesn't fix TB.
> 
> I just added
> Xft.dpi: 192
> to ~/.Xresources and not only TB works but LibreOffice works too.
> Of course all of this defies the purpose of having an HiDPI laptop but
> it is either that or no use at all.

For Qt apps you might want these environment variables in .xinitrc:

QT_SCREEN_SCALE_FACTORS=DVI-I-0=1.5;DVI-I-1=1.5;HDMI-0=1.5;DP-0=1.5;DP-1=1.5;DP-2=1.5;DP-3=1.5;DP-4=1.5;DP-5=1.5;

(These device names are the same as what xrandr shows.)

QT_AUTO_SCREEN_SCALE_FACTOR=0

Currently I have an issue where opening Qt apps from certain contexts results in resetting the DPI scale to 2 instead of 1.5. Primarily this happens when Chrome launches a Qt-based viewer such as Kate, and sometimes it happens from Konsole. Have yet to file bugs.