fix( sidenav): corrected use of internal $toggleOpen()

src/components/sidenav/sidenav.js

@@ -275,6 +275,7 @@ function SidenavDirective($timeout, $animate, $parse, $log, $mdMedia, $mdConstan
      */
     function updateIsOpen(isOpen) {
       var parent = element.parent();
+      var focusEl = sidenavCtrl.focusElement();
 
       parent[isOpen ? 'on' : 'off']('keydown', onKeyDown);
       backdrop[isOpen ? 'on' : 'off']('click', close);
@@ -283,7 +284,6 @@ function SidenavDirective($timeout, $animate, $parse, $log, $mdMedia, $mdConstan
         // Capture upon opening..
         triggeringElement = $document[0].activeElement;
       }
-      var focusEl = sidenavCtrl.focusElement();
 
       disableParentScroll(isOpen);
 
@@ -304,12 +304,16 @@ function SidenavDirective($timeout, $animate, $parse, $log, $mdMedia, $mdConstan
      */
     function disableParentScroll(disabled) {
       var parent = element.parent();
-      if ( disabled ) {
+      if ( disabled && !lastParentOverFlow ) {
+
         lastParentOverFlow = parent.css('overflow');
         parent.css('overflow', 'hidden');
+
       } else if (angular.isDefined(lastParentOverFlow)) {
+
         parent.css('overflow', lastParentOverFlow);
         lastParentOverFlow = undefined;
+
       }
     }
 
@@ -404,7 +408,7 @@ function SidenavController($scope, $element, $attrs, $mdComponentRegistry, $q) {
     return focusElement;
   };
 
-  self.$toggleOpen = function() { return $q.when($scope.isOpen); };
+  self.$toggleOpen = function(value) { return $q.when($scope.isOpen = value); };
 
   self.destroy = $mdComponentRegistry.register(self, $attrs.mdComponentId);
 }