High-DPI GNOME update: great progress, remaining issues

[Brion Vibber <brion pobox com>]

I've finally had a chance to test out the high-DPI display support that Alex Larsson added to GTK3/GNOME and presented at GUADEC last year -- it's looking awesome!

There's still some bugs (I'm testing out Fedora 20 plus the 3.12 packages, in Parallels on a 15" Retina MacBook Pro, with GDK_SCALE=2 in /etc/environment) but basic support is looking really good. Most of the bugs I see in base GNOME apps look like simple things like missing high-resolution artwork, or a low-level drawing surface that's at the wrong scale factor. I'm going to write up & file those bugs, and if I can I'll try to take a crack at patching some of them.

The biggest oddity with GNOME proper I see is that the Shell's UI displays at half-size, like it's ignoring the scaling. I might just be setting the GDK_SCALE improperly though...

There are also some bigger issues still remaining, among which a key problem is that legacy GTK2 apps like Firefox, Gimp and Inkscape don't scale up at all, and display super-tiny. (I filed a bug with Mozilla for Firefox to support the scaled mode properly in its in-progress GTK3 branch.)

It seems to me that the desktop compositor could double the displayed size of windows from those apps and display them pixelated, but the right size -- this is essentially what Mac OS X and Windows do with legacy apps. But I have no idea about those levels of the desktop stack, or how to distinguish windows that are high-DPI-aware from those that aren't, so I can't dive right in and try to make that work just yet...

Does anybody have any recommendations on looking into that, or is that a dangerous direction to look in? Is advocacy for porting to GTK3 more worthwhile time spent?


(And of course, I'll have to try it out under Wayland -- any recommendations there?)

-- brion vibber (brion @ pobox.com / brion @ wikimedia.org)