[PD] GEM: texturing parts of multiple movies

[Georg Holzmann]

Hallo!

I have the following (basic) GEM problem (and some ascii-art ;) :

I have 2 movies running with pix_film which are rendered on rectangles 
with the same size over the whole screen and I want to see only a part 
of each movie (see illustration):

from movie A:
-------------------------------
|                             |
|                             |
|                             |
|  |-------|                  |
|  | partA |                  |
|  |       |                  |
|  |-------|                  |
-------------------------------
from movie B:
-------------------------------
|                |--------|   |
|                | partB  |   |
|                |        |   |
|                |--------|   |
|                             |
|                             |
|                             |
-------------------------------
together:
-------------------------------
|                |--------|   |
|                | partB  |   |
|                |(movieB)|   |
|  |-------|     |--------|   |
|  | partA |                  |
|  |(movieA|                  |
|  |-------|                  |
-------------------------------

So I tried to lay black rectangles over the movies and let free 
partA,partB so that one can only see these parts. But this does not work 
for multiple movies, because then I only see the movie with the highest 
gemhead priority (and also with alpha blending it was not possible) ...

So my question: is this possible without additional pix_* commands ? 
(e.g. texturing only a part of the movie onto a rectangle ... ?)
If yes has someone an idea how ?

Thanks for any hint,
LG
Georg

PS: if this is too confusing I can send an example patch ;)