Thanks Ken,
I know, documenting all features of ltk is an awful lot of work, but maybe if it is divided into pieces and done by several people it is manageable with not too much effort.
And, as you probably know, Peter is German (as I am, too) and Germans opt for perfection ;-)
By the way, I have meanwhile been able to solve the problem myself, as I found a bigger piece of code that is written using ltk (clmail :
http://hocwp.free.fr/glmf/article_clmail/clmail-v2/) and by analyzing this I was able to use the already implemented function "scrolled-text". So Peter has obviously already implemeted it.