code: func (v *TextView) WindowToBufferCoords(win TextWindowType, window_x, window_y int) (buffer_x, buffer_y int) {
  	var bx, by C.gint
  	C.gtk_text_view_window_to_buffer_coords(v.native(), C.GtkTextWindowType(win), C.gint(window_x), C.gint(window_y), &bx, &by)
  	return int(bx), int(by)
  }
docs: // WindowToBufferCoords is a wrapper around gtk_text_view_window_to_buffer_coords().