One block touched by a text selection, and that block's text with the
selection boundaries marked.
text is the block's entire plain text with two private-use sentinel
characters (U+F000 and U+F001) inserted where the selection starts and ends.
Storing marked-up text rather than character offsets is what lets a highlight
survive edits elsewhere in the same block.
One block touched by a text selection, and that block's text with the selection boundaries marked.
textis the block's entire plain text with two private-use sentinel characters (U+F000 and U+F001) inserted where the selection starts and ends. Storing marked-up text rather than character offsets is what lets a highlight survive edits elsewhere in the same block.