TESH hasn't been updated in ages , it is doomed to die. Sfilips lost the source code so the only maintainance comes from hacks, so nothing
beyond new keywords will ever get added to TESH. If it hasn't died for you yet, it will die eventually.
Ah, the joys of being able to show why freeware should use open source licenses...
Folding in jEdit beats TESH' completely. It also does have auto-complete. It even has text auto-complete which is ridiculously good at saving time. I dunno about parameters, though you don't really have to remember arguments' names so I never really needed that feature more than highlighting of library functions/stuff.
Newgen itself is a bunch of useless BS that doesn't work in most computers so it has to go to hell.