Just bought a Toshiba Satellite P55t-B5262 4K laptop with a Radeon™ R9 M265X graphics card. Is there support for this card yet? When trying Ubuntu via USB, I found I was only able to see the GUI when a lower-resolution monitor was connected via the HDMI port (with general rendering errors). I have not yet gone through the process of a dual-boot install on this machine.

How well does 14.04.x LTS support touch screen devices? Are there significant touch-related & high-dpi improvements in 14.10.x?

Additionally, have others found success running Ubuntu on a ~4K monitor? There are plenty of Retina Ubuntu instances out there... do the various graphical elements scale well? Many thanks!