find-line

Given a graphical location in the editor, returns the line at that location. Lines are numbered starting with 0.

The result is only valid when the editor is displayed (see Basic Organization). Calling this method may force the recalculation of location information, even if the editor currently has delayed refreshing (see refresh-delayed?).

• (send a-text find-line y on-it?) -> exact non-negative integer
      y : real number
      on-it? = #f : boxed boolean or #f

  The on-it? box is filled with #t if the line actually touches this position, or #f otherwise, unless on-it? is #f. (A large enough y will always return the last line number, but will set on-it? to #f.)