Multi-Stream Transport 4K Monitors To Become Better Supported On Linux
Within the Linux 3.17 kernel and newer, the DP MST support is coming together on the kernel-side but from user-space there's ongoing work still being done. Keith Packard in looking to improve the DP MST support for 4K displays that consist of two panels, is adding a "Monitor" data type to RandR 1.5. GNOME relies upon the RandR data while KDE is using the (correct) Xinerama data for configuring the display. The Monitors protocol addition to RandR will make it on par to the Xinerama handling of these MST-based displays.
Keith has separate branches right now of the RandR protocol, libXrandr, xrandr, and the X.Org Server for supporting this Monitors addition to fix things up. For the full, lengthy explanation about the work Keith is doing, stop by his blog.
For those looking for an affordable but nice office 4K monitor that works fine under Linux, checkout the Acer B286HK 28-inch 4K DP/HDMI/DVI monitor. This happens to be the monitor I use on my main office system and is a bargain with sales putting it around $350 USD.