Ticket #28822: 28822.4.diff

src/wp-includes/js/media-views.js

@@ -4897 +4897 @@
                                 selection.single( model );
                                 return;
                         } else if ( 'add' === method ) {
-                                selection.add( model );
-                                selection.single( model );
+                                if ( this.selected() ) {
+                                        selection[ 'remove' ]( model );
+                                } else {
+                                        selection.add( model );
+                                        selection.single( model );
+                                }
                                 return;
                         }