Server-side rendering primitives:
# Apply to regions, rendered in fixed order, each has an ID
> Auto-scaling bitmaps
- - Control backed by an image with three five regions per axis
+ - Control backed by an image with three/five regions per axis
Edge Fixed, Fill, Center Fixed, Fill, Edge Fixed
- Definition is via two pixel counts (edge width, fill width), rest is derived
- Command to switch backing image to another already provided