get-scroll-page in canvas%

Get the current page step size of a manual scrollbar. The result is 0 if the scrollbar is not active or it is automatic.

See also init-manual-scrollbars.

• (send a-canvas get-scroll-page which) -> exact integer in [1, 10000]
     which : symbol in '(horizontal vertical)

  The which argument is either 'horizontal or 'vertical, indicating whether to get the page step size of the horizontal or vertical scrollbar, respectively.