~jaro/balkon

ref: 13b3a637336eb3490d6379a76472c90e54a1c01b balkon/src/Data/Text/ParagraphLayout/Internal/ProtoLine.hs -rw-r--r-- 3.7 KiB 
Allow explicit control of box collapsing.

Add extensible filter for invisible lines.

Handle ancestor boxes in rich layout.