I am sure this has been mentioned before, but to add weight to the feature request I will repeat it here:
the fundamental problem is that the best background for editing is black so it doesn’t hurt your eyes, but paper is white, not black. Therefore the colors that are good and visible for editing tend to be bad and not visible for printing.
there are currently two workarounds that I am aware of, both of which are clunky:
(1) manually edit your layer colors each and every time you switch from edit to print or back. this is a pain.
(2) set background to gray and select layer colors that sort of show up in both edit and print mode. this is non-optima and hard on the eyes (and we spend many many hours staring at your screen).
one potential solution is to be able to add the ability configure the edit and print colors separately.
thank you for your work on QCAD. It is a great program and this is entered not as criticism but in the spirit of trying to help make it ever better.