- /** Break the element if possible, so that its width is less
- * than \param w. Returns true on success. When \param force
- * is true, the string is cut at any place, other wise it
- * respects the row breaking rules of characters.
+ /** Break the element in two if possible, so that its width is less
+ * than the required values.
+ * \return true if something has been done ; false if this is
+ * not needed or not possible.
+ * \param width: maximum width of the row.
+ * \param next_width: available width on next rows.
+ * \param force: if true, cut string at any place, even for
+ * languages that wrap at word delimiters; if false, do not
+ * break at all if first element would larger than \c width.
+ * \param tail: a vector of elements where the remainder of
+ * the text will be appended (empty if nothing happened).