"eh" and "ev" only enable horizontal and vertical orthogonal modes (respectively). They do not let the user "snap perpendicular" (as implemented in other CAD packages such as AutoCAD).
Thanks for the update. I have been looking forward to the release of QCAD 3 for a while. Snap Perpendicular was something I used often in other CAD programs and missed it in QCAD 2 (although I found less convenient ways to accomplish the same thing in QCAD 2).