Posted by MrCAD on Oct 17, 2020; 4:42pm
URL: https://forum.librecad.org/Drawing-a-line-of-specific-length-like-in-AutoCAD-tp5719608p5719633.html

Well it was quite annoying at first place.

However, I did edit the librecad.alias for the line commands such as Horizontal, and Vertical, is assigned as H and V respectively. Shortcuts help to draw faster than number of times clicking the icons.

Here what I do if I need to draw a Horizontal Line (same with Vertical Line too):
1) Type H > Space/Enter
2) Type Tab and Space/Enter (quickly)
3) Type the length required > Space/Enter
4) Click the Left Mouse button (at snap point and click)

Please note that this trick doesn't work with these fellows...
 

Although you have solution to assign shortcut for Lengthen   command in which you will find the solution as above mentioned trick for Angular Lines especially.

Hope this help you out !!!