Awesome, thanks for that! By the way: that integration has been co-opted for use by a bunch of overlay software, like gw2taco [1].
So, even if not used for Mumble, it's now a pretty big feature for other 3rd party software. I use it regularly myself.
(For the unfamiliar: gw2taco et al use position/viewport data, I guess, from the GW2 Mumble API to draw an overlay on top of the game with navigational markers/aids.)