How to report bugs and request support?

First, some background on how to ask good questions:
 http://www.chiark.greenend.org.uk/~sgtatham/bugs.html

https://www.viget.com/articles/tips-for-writing-better-bug-reports

A good bug report/support request helps developers to understand the report, locate the root cause, and eventually fix this problem.

Ideally, a report should be specific with enough details for a developer to identify the issue. There is no need for several rounds of communication requesting clarification and support files.

One example of a bug report with enough details for a developers to follow the exact steps:

start librecad;
command line: line
when prompted "Specify first point", type in coordinates: 0,0 , and press enter;
at prompt "Specify next point", type in coordiante: @10, 10;
at prompt "Specify next point", type in coordiante: @-10, 10;
in command line, type in command lengthen;
in the option widget within the top widget area, type in length 100 and press enter;
click on the line from 0,0 to 10, 10, close to the 10, 10 end point.
Expected results: the line (0,0)-(10,10) is extended by 50 from the (10, 10) end.

Please attach a test case dxf, when necessary. We probably don't want your classified drawings, but do create some scratches to show the bug you found.