screencast sends old frames in multi-monitor layout
Sometimes old frames are send when using screencast with multiple monitors. This appears to happen, when a monitor other than the one being casted is updated.
Video of this: https://benjamin.sipsolutions.net/20190103_153858.mp4
In the video, the streamed video becomes jerky as soon as the window overlaps to the right (onto the second monitor).
15:47 < jadahl> the monitor screen cast src records frame on stage paints 15:48 < jadahl> but when you drag a window on both monitors, each "frame" will be two stage paints 15:48 < jadahl> so what it *should* do is listen on stage paints only on the correct view 15:50 < jadahl> so the meta-screen-cast-monitor-src.c needs to change what signal it listens to, or we need to add a way to find out what ClutterStageView (i.e. MetaRenderview, which should have a MetaLogicalMonitor associated with it if there are multiple stage views at all) 15:51 < jadahl> feaneron is working on explicit framebuffer passing, so maybe we can somehow pass the view around too