Ports using GTK2 and XQuartz status of HiDPI ("retina") support?

[github.20050610 at spamgourmet.com]

Hi,

I have installed the claws-mail port on a rMBP running MacOS Sierra 10.12.2 and unfortunately it looks pretty bad with marked aliasing. My desktop is usually scaled to 1440x900 but the effect is equally bad in other resolutions, including 1280x800. The native resolution of the display is 2560x1600 and cannot normally be chosen as working resolution in MacOS.

It seems that both XQuartz and GTK2 are not capable of handling HiDPI while things should work with Xrandr and GTK3:

​https://github.com/XQuartz/xquartz-old-tickets/blob/master/ticket/661.md
https://bugs.freedesktop.org/show_bug.cgi?id=92777​
https://wiki.archlinux.org/index.php/HiDPI
https://www.reddit.com/r/linux/comments/4v08jz/how_is_hidpi_these_days/d5ucqv3/

Attempts to port Claws Mail to GTK3 unfortunately seem to have stalled:

​https://forums.gentoo.org/viewtopic-t-1026670-start-0.html
​http://www.thewildbeast.co.uk/claws-mail/bugzilla/show_bug.cgi?id=2371

The same sadly has to be said about efforts to integrate Claws Mail with native OSX GTK:

​http://www.thewildbeast.co.uk/claws-mail/bugzilla/show_bug.cgi?id=3381
http://lists.claws-mail.org/pipermail/users/2015-May/013032.html

With Xrandr and GTK2 I achieved mixed results:

$ xrandr -q

provides the following information:

xrandr: Failed to get size of gamma for output default
Screen 0: minimum 640 x 480, current 1440 x 878, maximum 2560 x 1600
default connected 1440x878+0+0 0mm x 0mm
   2560x1600     60.00  
   1280x800      60.00  
   2048x1280     60.00  
   1650x1050     60.00  
   1440x900      60.00     2.00  
   1152x720      60.00  
   840x524       60.00  
   1024x768      60.00  
   800x600       60.00  
   640x480       60.00  
   1440x878       1.00*

I can get to a full resolution XQuartz screen with Xrandr:

$ xrandr --output default --mode 2560x1600 --dpi 192

but the DPI setting appears to have no effect on the now tiny looking Claws Mail.

Adding

Xft.dpi:192

to ~/.Xresources or using the command

$ defaults write org.macosforge.xquartz.X11 dpi -int 192

helps with that. Now I can use

$ xrandr --output default --mode 2560x1600

to get a decent looking claws-mail, however, in fullscreen XQuartz only. The Claws Mail titlebar and mouse cursor are tiny, the rest looks ok. Maximizing the Claws Mail window will expand the application window only to the upper left quarter of the screen, but I can drag the window corners to fullscreen size. If I use the Macbook Pro as a Synergy server with another computer's screen to the right, the mouse cursor will jump to that screen whenever I move it to the upper right corner of the XQuartz screen, which in some aspects appears to act like 4 screens.

I have found no way to make this to work in a non-fullscreen XQuartz window.

Is this as good as it gets? How do other users deal with this on their HiDPI Macs? Are ports which use GTK2 and XQuartz simply unsuited for retina devices? Does nobody use Claws Mail on Mac OS?

Looking forward to reading other's experiences.