Lines' Length and Orthogonal Axis Lock

You will be able to set either the next coordinate or to write just the length for line (in command line) and the line will be drawn accordingly.
You can also lock drawing to make it that you can move mouse just parallel with main axis. This works internally as a Solver mechanism, so in some cases that disable solver all-together may seem to not work, but in general with every shape drawn you will have this possibility.
To use it, you may check the nightly build.