~jaro/balkon

ref: b36dcd9859e8d5209a08186555b8f799ad2c8b0f balkon/src/Data/Text/ParagraphLayout/Internal/Rich.hs -rw-r--r-- 3.1 KiB 
Link ResolvedSpan to boxes.

Separate WithSpan for sharing with other modules.

Add basic support for Rich layout.