diff --git a/runtime/doc/popup.txt b/runtime/doc/popup.txt
index 52d0892..d696e28 100644
--- a/runtime/doc/popup.txt
+++ b/runtime/doc/popup.txt
@@ -1,4 +1,4 @@
-*popup.txt*  For Vim version 8.1.  Last change: 2019 Jul 18
+*popup.txt*  For Vim version 8.1.  Last change: 2019 Jul 28
 
 
 		  VIM REFERENCE MANUAL    by Bram Moolenaar
@@ -335,6 +335,10 @@
 
 		If popup window {id} is not found an empty Dict is returned.
 
+popup_getpreview()					*popup_getpreview()*
+		Get the |window-ID| for the popup preview window.
+		Return zero if there is none.
+
 
 popup_hide({id})						*popup_hide()*
 		If {id} is a displayed popup, hide it now. If the popup has a