For me the context menu of the tray icon is totally broken:

System: Ubuntu 18.04 LTS, x86_64 Linux 4.15.0-30-generic
Desktop: MATE 1.20.0 (wm: Metacity)
Steam client: Aug 1st 2018
It would be appreciated if I could at least disable the tray icon in the settings (many devs consider a tray icon usage like that to be deprecated anyway).
I fixed this issue on my system by installing the 32 bit libdbusmenu library: sudo apt install libdbusmenu-gtk4:i386
Steam will use those instead of the apparently broken ones from the runtime. But still, it should be possible to disable this in the settings.
Update:
It seems the pinned libraries just needed an update. I didn't need to install libdbusmenu-gtk4:i386, instead I just had to remove the ~/.steam/ubuntu12_32/steam-runtime/pinned_libs_* directories. Maybe the pinned libs should be checked on every update or so?
Nothing extracted yet.
Your system information
4.17.8-1-ARCH x86_64 bits: 64 Desktop: Cinnamon 3.8.8
Please describe your issue in as much detail as possible:
Left or right-clicking on the Steam tray icon produces the context menu as it should, but since the Friend List update I can no longer set my status via menu. I cannot set myself Offline and I cannot add the new options (Invisible) to the tray menu via Steam preferences.
In fact I am having several issues with the new Friend List, but I am limiting this post to just this issue.
Steps for reproducing this issue: