The indeterminent progress indicator in the AppDetails view is now hidden by default on Android 4.0.3 (which is the only reproducing device I had access to). Had to replace a bunch of calls with those provided by appcompat.
As for the "(De-)Installation Error" message when using the root installer, it was due to the timeout being set to 5 seconds for the superuser shell. Note that just accepting the super user prompt takes a minimum of 3 seconds, plus the install time. I changed the timeout to 30 seconds, for reasons explained in the commit.
NOTE: @mvdan, I noted that you mentioned you were not interested in client development any more, so I'm not quite sure if it is worthwhile me submitting this as a MR (FYI - thanks for all the help on the client, also happy that your able to spend more time on build recipies and fdroidserver stuff. Great to see all that moving along). Perhaps @CiaranG, if you had the time to review it you could give it the thumbs up or down? Otherwise, I'll merge it myself.