Digging further into this, I suspect that the issue is related to this error: Xlib: extension "XTEST" missing on display ":0".
I would guess that the Steam client is using xtest to send keyboard and mouse events to the OS. My Fedora install doesn't seem to have a working xtest. Still digging into this.
Finally fixed it. On my install, for some reason I had to add an /etc/X11/xorg.conf.d/01-xtext.conf containing:
Section "Extensions"
Option "XTEST" "on"
EndSection
Nothing extracted yet.
I just received my Steam controller, and am trying to make it work with Steam on my Fedora 22 install. The most annoying bug so far is that once steam launches, any button press results in a segfault.
Dmesg shows : CSteamControlle[4822]: segfault at a0 ip 00000000ed8389d4 sp 00000000eb956d60 error 4 in steamclient.so[ed400000+113b000]
I've added the udev rules, disabled selinux, etc and nothing seems to help. Once big picture mode is started, the controller behaves as expected, except that when a game is launching, again a button press segfaults steam with the same output.