Code review comment for lp:~donadigo/slingshot/show-app-badges

you might want to overthink implementing it that way
e.g. https://bugs.launchpad.net/plank/+bug/1514201 a DDoS-like scenario

you need to update only once when you open slingshot or switch an app page, so you don't need to listen all the time

maybe even plank could provide those values via dbusclient