15' MBP 2016's native screen resolution is 2880x1800 but in Parallel the maximum screen resolution is 3360x2100. This bug leads to an blurry screen of my Windows XP virtual machine no matter how I adjust the display settings. IMO, parallel can just map 1 pixel to 4 pixels and show a sharp and clean 1440x900 screen on 2880x1800 HiDPI screen.
Problem solved. The 2016 15' MBP's default resolution is 1680x1050 which you can set in "System Preferences" > "Displays" and that's the reason why my virtual machines maximum screen resolution is 3360x2100. If I change "Displays" resolution settings to 1440x900 everything works as expected!
Strange... I've got Acer Predator X34, 34" Curved Display (21:9 Aspect Ratio) with 3440 x 1440 (native and maximum) Resolution. Have no problem, maybe you should try it system charactiristics?
