[NTG-context] MP: problems with dashed lines

Hi, I wanted to use dashed lines as folding marks, but apparently they only work with pencircle, or at least not with pensquare. The Metafun manual (Reference, C5) also shows a problem with "dashed oddly", that I can’t reproduce in this MWE: \startMPpage draw (0,0)--(100,100) withpen pencircle dashed evenly; draw (50,0)--(150,100) withpen pencircle dashed oddly; draw (100,0)--(200,100) withpen pensquare dashed evenly; % plain line, not dashed draw unitsquare scaled 100 withpen pencircle dashed oddly withcolor blue; draw unitsquare scaled 100 xshifted 50 withpen pensquare dashed evenly withcolor red; \stopMPpage Hraban