Just got my XPS 13 9350 with a 3200 x 1800 screen. However the graphics card does not support the highest resolution. Intel(R) Iris(TM) Graphics 540. When set to 3200 x 1800 some of the cursors on the screen are the size of pin head Tried a bunch of things with tech support and they said I just have to wait until there is an updated Intel driver.
It is not the driver that's the issue - it's the application. Some applications have trouble with scaling to ultrahigh resolution. For those, you'll need to contact the publisher to see if updates or upgrades are available - or look for alternatives that do support scaling -- or consider returning the system for one with an FHD screen if they're not.