(wl-summary-buffer-window-scroll-functions):

(wl-summary-buffer-window-scroll-functions):
Renamed from wl-summary-window-scroll-functions.
(wl-summary-window-scroll-functions): Don't set to variable.
(wl-summary-display-top): Use run-hooks.
(wl-summary-display-bottom): Ditto.
(wl-summary-toggle-disp-msg): Ditto.
(wl-summary-mode): Set wl-summary-buffer-window-scroll-functions;
Use it instead of wl-summary-window-scroll-functions.
(wl-summary-goto-folder-subr): Don't call
wl-summary-window-scroll-functions, use
wl-summary-buffer-window-scroll-functions instead.