Use the system gtk theme

[niemeyer]

We just had a call to sync up on the progress of this work. Here are the details:

Desktop improvements report and plans

Hello all, We’ve just had a good call (and rather long, thanks to @zyga-snapd and @jamesh for taking the time) to synchronize on the status of the on going desktop support improvement and the plan for the upcoming weeks. I’ll summarize what we discussed below. Let’s please keep this topic only to discuss the work organization. If you’d like to discuss any of the particular changes, please go to the respective topics linked from here. Themes The work on themes was parked for a while waiting on…