Where would I find thoses, or an overview of them?
There is a chapter in the Help>Appendix>Configuration Variables, but it maybe doesn't cover
all of them.
There is an add. 'overview' in your <SE config-dir (see Help->About)>\
vusrdefs.e file. You know - only the source tells the truth
Their names often give a certain idea about the purpose and quite a number of them are commented in the product sources.
But for most people it's impossible to know all of them.
Usually someone asks for a certain feature/behaviour in the forum or even better do a 'Search' first. It's quite likely that someone (other users/SlickTeam) already posted something, posts an answer/hint or tell you that it's not (yet) possible as the worst case.
However, quite a lot can be done using the GUI. Id propose to try that before dealing with all the confusing def_<vars>.
HS2