Hi,
First off, I just discovered LibreCAD a few weeks ago and have now dropped QCad entirely. Great stuff!
The "Draw Parallel Line Through" action is broken in master. Often the new line does not show up at all; if the reference point is close to the selected entity, the line shows up, but it doesn't go through the reference point. The problem was that RS_ConstructionLine::getDistanceToPoint() was returning a nonsensical value. Attached is a patch.
Tim
0001-fix-bugs-in-RS_ConstructionLine-getDistanceToPoint.patch