When entering or leaving the alternate screen, discard any pending

resizes. Improves flicking with scrollbars and programs that leave and
enter the alternate screen on every WINCH like nano. GitHub issue 4772.

Cvs: ----------------------------------------------------------------------

screen-write.c

@@ -2765,16 +2765,22 @@ void
 screen_write_alternateon(struct screen_write_ctx *ctx, struct grid_cell *gc,
     int cursor)
 {
-	struct tty_ctx		 ttyctx;
-	struct window_pane	*wp = ctx->wp;
+	struct tty_ctx			 ttyctx;
+	struct window_pane		*wp = ctx->wp;
+	struct window_pane_resize	*r, *r1;
 
 	if (wp != NULL && !options_get_number(wp->options, "alternate-screen"))
 		return;
 
 	screen_write_collect_flush(ctx, 0, __func__);
-	screen_alternate_on(ctx->s, gc, cursor);
+	if (!screen_alternate_on(ctx->s, gc, cursor))
+		return;
 
 	if (wp != NULL) {
+		TAILQ_FOREACH_SAFE (r, &wp->resize_queue, entry, r1) {
+			TAILQ_REMOVE(&wp->resize_queue, r, entry);
+			free(r);
+		}
 		layout_fix_panes(wp->window, NULL);
 		server_redraw_window_borders(wp->window);
 	}
@@ -2796,7 +2802,8 @@ screen_write_alternateoff(struct screen_write_ctx *ctx, struct grid_cell *gc,
 		return;
 
 	screen_write_collect_flush(ctx, 0, __func__);
-	screen_alternate_off(ctx->s, gc, cursor);
+	if (!screen_alternate_off(ctx->s, gc, cursor))
+		return;
 
 	if (wp != NULL) {
 		layout_fix_panes(wp->window, NULL);

screen.c

@@ -655,13 +655,13 @@ screen_reflow(struct screen *s, u_int new_x, u_int *cx, u_int *cy, int cursor)
  * Enter alternative screen mode. A copy of the visible screen is saved and the
  * history is not updated.
  */
-void
+int
 screen_alternate_on(struct screen *s, struct grid_cell *gc, int cursor)
 {
 	u_int	sx, sy;
 
 	if (SCREEN_IS_ALTERNATE(s))
-		return;
+		return 0;
 	sx = screen_size_x(s);
 	sy = screen_size_y(s);
 
@@ -677,10 +677,12 @@ screen_alternate_on(struct screen *s, struct grid_cell *gc, int cursor)
 
 	s->saved_flags = s->grid->flags;
 	s->grid->flags &= ~GRID_HISTORY;
+
+	return 1;
 }
 
 /* Exit alternate screen mode and restore the copied grid. */
-void
+int
 screen_alternate_off(struct screen *s, struct grid_cell *gc, int cursor)
 {
 	u_int	sx = screen_size_x(s), sy = screen_size_y(s);
@@ -709,7 +711,7 @@ screen_alternate_off(struct screen *s, struct grid_cell *gc, int cursor)
 			s->cx = screen_size_x(s) - 1;
 		if (s->cy > screen_size_y(s) - 1)
 			s->cy = screen_size_y(s) - 1;
-		return;
+		return 0;
 	}
 
 	/* Restore the saved grid. */
@@ -731,6 +733,8 @@ screen_alternate_off(struct screen *s, struct grid_cell *gc, int cursor)
 		s->cx = screen_size_x(s) - 1;
 	if (s->cy > screen_size_y(s) - 1)
 		s->cy = screen_size_y(s) - 1;
+
+	return 1;
 }
 
 /* Get mode as a string. */

server-client.c

@@ -1590,10 +1590,7 @@ server_client_resize_timer(__unused int fd, __unused short events, void *data)
 static void
 server_client_check_pane_resize(struct window_pane *wp)
 {
-	struct window_pane_resize	*r;
-	struct window_pane_resize	*r1;
-	struct window_pane_resize	*first;
-	struct window_pane_resize	*last;
+	struct window_pane_resize	*r, *r1, *first, *last;
 	struct timeval			 tv = { .tv_usec = 250000 };
 
 	if (TAILQ_EMPTY(&wp->resize_queue))

tmux.h

@@ -1147,6 +1147,8 @@ struct window_mode_entry {
 	struct screen			*screen;
 	u_int				 prefix;
 
+	int				 kill;
+
 	TAILQ_ENTRY(window_mode_entry)	 entry;
 };
 
@@ -3335,8 +3337,8 @@ void	 screen_hide_selection(struct screen *);
 int	 screen_check_selection(struct screen *, u_int, u_int);
 int	 screen_select_cell(struct screen *, struct grid_cell *,
 	     const struct grid_cell *);
-void	 screen_alternate_on(struct screen *, struct grid_cell *, int);
-void	 screen_alternate_off(struct screen *, struct grid_cell *, int);
+int	 screen_alternate_on(struct screen *, struct grid_cell *, int);
+int	 screen_alternate_off(struct screen *, struct grid_cell *, int);
 const char *screen_mode_to_string(int);
 const char *screen_print(struct screen *, int);