patch 7.4.1817
Problem:    The screen is not updated if a callback is invoked when closing a
            channel.
Solution:   Invoke redraw_after_callback().
diff --git a/src/channel.c b/src/channel.c
index 4b7b6f7..444599c 100644
--- a/src/channel.c
+++ b/src/channel.c
@@ -2494,6 +2494,7 @@
 			   &rettv, 1, argv, 0L, 0L, &dummy, TRUE,
 			   channel->ch_close_partial, NULL);
 	      clear_tv(&rettv);
+	      channel_need_redraw = TRUE;
 	  }
 	  --channel->ch_refcount;
 
@@ -2503,6 +2504,12 @@
 	  partial_unref(channel->ch_close_partial);
 	  channel->ch_close_partial = NULL;
 
+	  if (channel_need_redraw)
+	  {
+	      channel_need_redraw = FALSE;
+	      redraw_after_callback();
+	  }
+
 	  /* any remaining messages are useless now */
 	  for (part = PART_SOCK; part <= PART_ERR; ++part)
 	      drop_messages(channel, part);