From a5f4a4dd7457bc99373e46e3732a278e3e783294 Mon Sep 17 00:00:00 2001
From: Mike Donahue <mtdonahue1@gmail.com>
Date: Thu, 28 Nov 2019 06:14:13 -0800
Subject: [PATCH] [Backdrop] Comment on z-index use case (#18589)

---
 packages/material-ui/src/Backdrop/Backdrop.js | 1 +
 1 file changed, 1 insertion(+)

diff --git a/packages/material-ui/src/Backdrop/Backdrop.js b/packages/material-ui/src/Backdrop/Backdrop.js
index e17c4e5a60a119..543bf69146e243 100644
--- a/packages/material-ui/src/Backdrop/Backdrop.js
+++ b/packages/material-ui/src/Backdrop/Backdrop.js
@@ -7,6 +7,7 @@ import Fade from '../Fade';
 export const styles = {
   /* Styles applied to the root element. */
   root: {
+    // Improve scrollable dialog support.
     zIndex: -1,
     position: 'fixed',
     display: 'flex',