1299897 - Widgets (scrollbar etc) don't respect HiDPI setting with GTK 3.21+

Status: RESOLVED WORKSFORME

(Core :: Widget: Gtk, defect, P2)

Description

[fabrixx2]

User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:50.0) Gecko/20100101 Firefox/50.0
Build ID: 20160615000543

Steps to reproduce:

I added the gnome-dev repository of Arch Linux and upgrade from Gnome 3.20 stable to Gnome-dev 3.21 on an UHD monitor.


Actual results:

After reboot Firefox interface and its characters have been drastically reduced in size, the text size of web pages has not changed


Expected results:

Whith Gnome 3.20  i've modified layout.css.devPixelsPerPx value to 2.5 in about config to fix similar problem but with Gnome 3.21 change have no effects.
the same problem occurs with Thunderbird and Seamonkey.

I tried to compile SeaMonkey from source with --enable-default-toolkit=cairo-gtk3 but I have not had changes.

I can fix problem with this code in userChrome.css:
@namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"); /* set default namespace to XUL */

 * {font-size: 15px !important;
}


This solves the problem only partially as context menus are out of position

Comment 1

[Makoto Kato [:m_kato]]

confirmed on Debian/sid with libgtk-3 3.21.5-3

Comment 2

[Makoto Kato [:m_kato]]

gdk_screen_get_monitor_scale_factor always return 0 on X11 backend after the fllowing landing on GTK3.  I should file a bug to GTK.

commit d92fda2103bc79043465b5218323a14edd05183e
Author: Matthias Clasen <[e-mail]>
Date:   Sun Apr 3 00:12:39 2016 -0400

    x11: Port to new monitor api

Comment 3

[Makoto Kato [:m_kato]]

GTK 3.22 introduce new gdk_monitor_get_scale_factor API for this...

Comment 4

[Makoto Kato [:m_kato]]

s/always return 0/always return 1/

Comment 5

[Makoto Kato [:m_kato]]

When I test on GTK 3.22, I verify this.  Mark as WFM.