get-scroll-pos in canvas%

Gets the current value of a manual scrollbar. The result is always 0 if the scrollbar is not active or it is automatic.

See also init-manual-scrollbars.

• (send a-canvas get-scroll-pos which) -> exact integer in [0, 10000]
     which : symbol in '(horizontal vertical)

  The which argument is either 'horizontal or 'vertical, indicating that the value of the horizontal or vertical scrollbar should be returned, respectively.