Valve have today put out a stable Steam Client update pulling in lots of changes from the previous beta version, it's a good one too.
In terms of what's changed for Linux specifically:
- Added a 2X-scaling mode with high-res text and graphics when running the Steam client in desktop mode on 4k-resolution monitors. You can also force 2X scaling with the "GDK_SCALE=2" environment variable, or disable it with "GDK_SCALE=1".
- Improved window-resizing interactions with the window manager
- Fixed an issue where the Steam client could prevent some desktop sessions from shutting down
Some seriously welcome stuff there from Valve—good work. The bug about preventing shut downs was a particular nuisance I'm really glad to see the back of.
They also worked to reduce CPU use when the mouse is moved back and forth over part of the Library view, fixed a problem with corrupted Workshop items endlessly re-downloading and they fixed a strange issue where some games wouldn't launch in offline mode if Steam had previously started or scheduled an update.
On top of that, there's numerous fixes and improvements to Steam Input, for interacting with the Steam Controller and various other gamepads.
See the full update notes here.