after-set-position in text:info-mixin

Called after the start and end position have been moved (but not when the position is moved due to inserts or deletes).

See also on-edit-sequence.

• (send a-text:info-mixin after-set-position) -> void

  Calls the editor-position-changed method of the frame that is viewing this object. It uses get-canvas to get the canvas for this frame, and uses that canvas's top-level-window<%> as the frame.