New layer makes lines all go really long on bottom layer

Win 7 64 bit
Version: 2.1.3
Compiler: GNU GCC 4.9.1
Compiled on: Sep 23 2016
Qt Version: 5.4.1
Boost Version: 1.60.0
System: Windows 7

I drew a drawing and then added a layer, copying a couple of entities from Layer 0 to Layer 1.

When I did this, some 2 points lines that I had drawn on the bottom layer suddenly went very long: right to the bounds of the drawing' They may actually be infinite. As much as I zoom out they go right to the edges.

Any new lines that I draw, by whatever method, on Layer 0 also go way out. I set the 1st point, drag to my next point and release: the line just goes far away out in both directions.

Rectangles etc are OK. Curves are OK. Just straight lines.

I started a new drawing and this does not happen. It is just two lines, started on Layer 0 then one of them is moved to Layer 1.

Any help appreciated.

Nick

You have activated construction layer.

Thank you for the reply.

I am pretty sure all I did was ask for a new layer, as in +. In my drawing I can see no Construction Layer option.

Anyway, what on earth is a construction layer, that causes this? What is its purpose? It seems crazy. It does not behave logically.

OK. How do I fix the problem? Can I change my Construction Layer to ordinary, confused people's layer?

Also, it was acting on lines that I had already drawn in the bottom layer. I can't see any sense in the behaviour, even if I did what you say.

Nick

The purpose of a construction layer is not to be a part of the visible drawing but as an aid to arrange objects, maybe relative to each other, begin at certain coordinates, find intersection points etc. It's an auxiliary layer, not to be printed. All straight lines are shown as infinite.
Just click on the hash symbol in the layer list, so it is greyed out, then it is a normal layer, and the infinite lines will disappear.

Thanks...but wow. Is that for a User, or a Geek? So easy to make such a weird effect? I still (as a User) have no idea what happens here.

Nick