Hi tytus,

Thank you for your post.

I am afraid that messages's names in Sequence Diagrams cannot be broken into lines.
Mainly names of Usecases, Lifelines in Sequence Diagrams, Actions in Activity Digrams and Text and a couple of more others are able to get broken into lines.

It must be a pain that letters get too small to see when you print a large size of diagram on one page.
I will sincerely add this to requested features list to improve JUDE!
Thank you.

-Sincerely yours,
satomi