use double for computing the device offset (we used negative uints, oops)
use double for computing the device offset (we used negative uints, oops)

Also use proper mark functions when drawing on the surface

mltframework/swfdec,mltframework/swfdec,freedesktop-unofficial-mirror/swfdec__swfdec,freedesktop-unofficial-mirror/swfdec__swfdec,freedesktop-unofficial-mirror/swfdec__swfdec