[Windows] When using Parallels on OS X to host Windows then Qt does not display properly on a retina display

[Windows] When using Parallels on OS X to host Windows then Qt does not display properly on a retina display. Initially it does not detect that it is on a HiDpi display so everything is displayed at a device pixel ratio of 1.0.

If this is worked around by setting it to 2.0 (or preferably auto) via QT_DEVICE_PIXEL_RATIO then it generally works fine except there is some truncation with comboboxes, radiobuttons, checkboxes and spinboxes.

Windowsstyle and Fusion style are fine in this regard. Attached are some screenshots to illustrate the issue.