Thank everybody for indispensible help, esp. Wolfgang. I owe yuo a beer :)

My project should be completed today, so it is probably one of the last 
questions.

I have set up \setupalign[stretch], after which my document looks far 
more justified (no ragged right text edge). However, in some difficult 
situations I still get the problem, as shown on attached shot. Moreover, 
TeX compains about a lot of overfull hboxes. How to instruct TeX to 
relax and allow more spacing between words (or more stretching?)

Best,
Vyatcheslav