+
+/* FIXME: This is a hack that we use to identify columns that used to
+ contain note-heads but whose note-heads were moved by one of the ligature
+ engravers. Once the ligature engravers are fixed to behave nicely, this
+ function can be removed.
+*/
+bool
+Paper_column::is_extraneous_column_from_ligature (Grob *me)
+{
+ if (!is_musical (me))
+ return false;
+
+ // If all the note-heads that I think are my children actually belong
+ // to another column, then I am extraneous.
+ extract_grob_set (me, "elements", elts);
+ bool has_notehead = false;
+ for (vsize i = 0; i < elts.size (); i++)
+ {
+ if (Rhythmic_head::has_interface (elts[i]))
+ {
+ has_notehead = true;
+ if (dynamic_cast<Item*> (elts[i])->get_column () == me)
+ return false;
+ }
+ }
+ return has_notehead;
+}
+
+
+ADD_INTERFACE (Paper_column,
+ "@code{Paper_column} objects form the top-most X@tie{}parents"
+ " for items. There are two types of columns: musical columns,"
+ " where are attached to, and non-musical columns, where"
+ " bar-lines, clefs, etc., are attached to. The spacing engine"
+ " determines the X@tie{}positions of these objects.\n"
+ "\n"
+ "They are numbered, the first (leftmost) is column@tie{}0."
+ " Numbering happens before line breaking, and columns are not"
+ " renumbered after line breaking. Since many columns go"
+ " unused, you should only use the rank field to get ordering"
+ " information. Two adjacent columns may have non-adjacent"
+ " numbers.",
+
+ /* properties */
+ "between-cols "
+ "bounded-by-me "
+ "full-measure-extra-space "
+ "grace-spacing "
+ "labels "
+ "line-break-system-details "
+ "line-break-penalty "
+ "line-break-permission "
+ "page-break-penalty "
+ "page-break-permission "
+ "page-turn-penalty "
+ "page-turn-permission "
+ "rhythmic-location "
+ "shortest-playing-duration "
+ "shortest-starter-duration "
+ "spacing "
+ "used "
+ "when "
+ );
+