...It displays the movement of a system of the material points which are interacting to each other.
Warning! Currently program's verison with OpenMotif GUI is working wrong! It's displaying everything good, but does not simulate gravitation, actually.
When author started writing this C-code, he was n00b, sorry :(
And he has no time to rewrite it.
Only simple Qt4 version really simulates gravity, but there's no other interactive controls except GL window itself, e.g. you have to change the parameters in code, recompile and run:
svn co https://xmgravdots.svn.sourceforge.net/svnroot/xmgravdots/branches/Qt4GravDots/ Qt4GravDots/