fix previous style madness
fix previous style madness

We now properly attach a stle, but override style_set. This ensures that the
window's background never gets updated on setting a style. Thanks to Benjamin
Berg for the idea.

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