No fundamental problem discovered thus far...
- GTK-3 does not resize the window, need to `set_size_request()` (instead of `resize()`)
- forgot to set slot-state to READ ⟹ submissions flood the full queue
- condition to allow frame display was too tight, thus slipping at first frame
- forgot to submit follow-up read tasks
This implies a basic decision regarding the buffer and state data to use,
and how this can be defined, parameterised and passed between threads.
I decided to place separation of domains first and to prefer
using a functional callback over using a shared data structure.
leaning heavily on the similar structure used for last year's
FrOSCon talk regarding video output (by Benny Lyons and myself).
However, this time we'll use a process state object (the player)
and, furthermore, there is some cross-wiring of components involved...
