the index of a line, which must be between 0 and <literal>pango_layout_get_line_count(layout) - 1</literal>, inclusive.
the requested #PangoLayoutLine, or %NULL if the index is out of range. This layout line can be ref'ed and retained, but will become invalid if changes are made to the #PangoLayout. No changes should be made to the line.
1.16
Retrieves a particular line from a #PangoLayout.
This is a faster alternative to pango_layout_get_line(), but the user is not expected to modify the contents of the line (glyphs, glyph widths, etc.).