[NTG-context] Vertically centered title page

Dear all, I am trying to build a presentation with specific requirements. I would like to have the title of the presentation on the middle (both vertical and horizontal) of the first page. I tried, on one hand, two \vfill, and, on the other hand, \framed[location=middle,align=middle] but without success. The title is always on the top of the text area. Any help is welcome ! -- Flavien. ---------------------------- "Quantum objects are completely crazy but, at least, they are all crazy in the same way." R.P. Feynman.