pub fn prev_file_boundary_row(
excerpts: &[Excerpt],
cursor_row: u32,
count: u32,
) -> Option<u32>Expand description
Composed row of the count-th file-boundary excerpt backward
of the boundary containing the current excerpt. A “file
boundary” is the FIRST excerpt of each file group (per
[E semantics: jump to the start of the previous file).