fix(launcher): Exception in GNOME 3.36 due to Shell.AppLaunchGPU being undefined

[mmstick]

Closes #1194

[jacobgkau]

Attempting to regression test this on Pop!_OS 20.04, using kitty as an example, I'm seeing wrong behavior even on the current version:

• Start from Activities -> doesn't use dGPU
• Start from Activities with dGPU -> uses dGPU
• Start from Launcher -> uses dGPU
• Start from Launcher with dGPU -> uses dGPU

The launcher seems to be starting this app on the dGPU every time, with no way to manually start on integrated graphics. As far as I can tell, this should not be the case, because its .desktop file does not have PrefersNonDefaultGPU set at all.

If I install Steam, which does have PrefersNonDefaultGPU set to true, the launcher gives me an option to launch on integrated graphics, but clicking it launches on discrete graphics anyway. (Clicking the same integrated option in Activities does launch on integrated.)

Any idea why this is happening, or should I just open a separate issue about it?

[mmstick]

I'll look into that

[matthewtraughber]

I'm very new to this, but I think these issues may be due to gnome-shell switching from gboolean to ShellAppLaunchGpu - enum defined here.

• 3.36.8/shell-app.c gboolean discrete_gpu
• main/shell-app.c ShellAppLaunchGpu gpu_pref.

I manually updated and applied this fix locally to the latest pop-os/shell version, and got the launcher working again. I then modified things a bit (below) based on my very limited understanding - however, I don't have a discrete/default GPU config to test implementation.

        let gpuPref = null

        if (!("AppLaunchGpu" in Shell)) {
            gpuPref = false
        } else {
            gpuPref = entry.gpu_preference === "Default"
                ? Shell.AppLaunchGpu.DEFAULT
                : Shell.AppLaunchGpu.DISCRETE;
        }