display on/off, dimming, lock is actually called by MCE (Mode Control Entity)
you can look at the mce.ini file but be very careful, if n900 can't read some settings it will not start. if you stick bad character in the wrong place, maybe you have to reflash

there's obviously some dbus command or window flags you can set to prevent sleep mode too, just try to find some open source video player and see how they do it.

if you really want to write to the framebuffer, search for directfb.

okay i see, you want it to freeze on the lock screen, without dimming... i would look at those mce.ini settings first, might be something in there.

here's some more dbus stuff you can try:
http://maemo.org/api_refs/5.0/beta/m...-names_8h.html