Hi niko, looks like you figured it out while I wrote my reply! :)

Construction lines only activate when you do the mouse drag gesture to activate them, so it is not quite as easy to find out about them without looking at a tutorial video or the documentation.

That's kind of a side effect of them staying out of your way until you specifically call on them.

The systems that activate by just hovering over a point are more discoverable by just messing around, but they have a bad side effect of triggering rather too easily and filling up the workspace with quite a lot of snap zones. When your whole screen gets filled with snap zones it can tend to cause a problem where you can no longer make fine adjustments to points in a freeform manner.

- Michael