diff --git a/polygerrit-ui/app/elements/diff/gr-diff-view/gr-diff-view.js b/polygerrit-ui/app/elements/diff/gr-diff-view/gr-diff-view.js
index 3c3536b..d6a3bc0 100644
--- a/polygerrit-ui/app/elements/diff/gr-diff-view/gr-diff-view.js
+++ b/polygerrit-ui/app/elements/diff/gr-diff-view/gr-diff-view.js
@@ -230,7 +230,13 @@
           }
           break;
         case 65:  // 'a'
-          if (!this._loggedIn) { return; }
+          if (e.shiftKey) { // Hide left diff.
+            e.preventDefault();
+            this.$.diff.toggleLeftDiff();
+            break;
+          }
+
+          if (!this._loggedIn) { break; }
 
           this.set('changeViewState.showReplyDialog', true);
           /* falls through */ // required by JSHint