+/* Set vertical scollbar BAR to have its upper left corner at (TOP,
+ LEFT), and be LENGTH rows high. Set its handle to indicate that we
+ are displaying PORTION characters out of a total of WHOLE
+ characters, starting at POSITION. Return BAR. If BAR is zero,
+ create a new scrollbar and return a pointer to it. */
+extern struct scrollbar *(*set_vertical_scrollbar_hook)
+ ( /* struct scrollbar *BAR,
+ struct window *window,
+ int portion, int whole, int position */ );
+
+
+/* The following three hooks are used when we're doing a thorough
+ redisplay of the frame. We don't explicitly know which scrollbars
+ are going to be deleted, because keeping track of when windows go
+ away is a real pain - can you say set-window-configuration?
+ Instead, we just assert at the beginning of redisplay that *all*
+ scrollbars are to be removed, and then save scrollbars from the
+ firey pit when we actually redisplay their window. */
+
+/* Arrange for all scrollbars on FRAME to be removed at the next call
+ to `*judge_scrollbars_hook'. A scrollbar may be spared if
+ `*redeem_scrollbar_hook' is applied to it before the judgement. */
+extern void (*condemn_scrollbars_hook)( /* FRAME_PTR *FRAME */ );
+
+/* Unmark BAR for deletion in this judgement cycle. */
+extern void (*redeem_scrollbar_hook)( /* struct scrollbar *BAR */ );
+
+/* Remove all scrollbars on FRAME that haven't been saved since the
+ last call to `*condemn_scrollbars_hook'. */
+extern void (*judge_scrollbars_hook)( /* FRAME_PTR *FRAME */ );
+
+
+