Accomplishments viewer should use single instance

[Rafał Cieślak]

Currently launching accomplishments-viewer several times results in multiple accomplishment windows open. This may be very annoying. e.g. when one browses the trophies via lens. Having clicked on several trophies he will open lots of Accomplishment Browser instances.

Ideally one window would be used to display that information. That would mean that running accomplishments-viewer -a [...] should check if there is already another instance running, and if so, it should tell that other already-running instance to show that particular accomplishment, and then the newly launched instance should quit immediately.

[Rafał Cieślak (rafalcieslak256)]

I have no idea if there is some standard approach for that-like bugs, maybe there is something pre-programmed in one of the standard libraries (I failed to find it, though).
However, I think it may be a good idea to send D-Bus message to another instance. If it fails, then it means there is no other instance running, so we continue normally. If it is sent successfully, then we quit immediately, as there must be some other instance of the Viewer running (the receiver). The other instance should react on that D-Bus message by showing accomplishment, whose ID was passed in this message.
Does that make sense?

[Alessandro Losavio (alo21)]

I tried a lot of ways to create a single instance, but I thinks, now as now, is not really possible do it. May be could be after some accomplishments-viewer's structure changes.

So I set this bug as 'Nobody' and as 'Confirmed'.