         {
             contentGroup.includeInLayout = contentGroupProps.start.includeInLayout;
             contentGroup.cacheAsBitmap = contentGroupProps.start.cacheAsBitmap;
+            
+            // The default tab bar hide and show animation will animate the width and height
+            // of the navigator's contentGroup.  If the explicitWidth or explicitHeight properties
+            // were NaN before the animation, they'll be set to real values by the animation.  As
+            // a result, it is necessary to restore them to NaN so that layout properly sizes these
+            // components. 
+            if (isNaN(contentGroupProps.start.explicitHeight))
+                contentGroup.explicitHeight = NaN;
+            
+            if (isNaN(contentGroupProps.start.explicitWidth))
+                contentGroup.explicitWidth = NaN;
+            
             contentGroupProps = null;
         }
     }

                
                if (activeView)
                    activeView.setTabBarVisible(showingTabBar);

                // When this flag is true, the animations should only be disabled for the 
                // current frame, so reset the flag so animations play on subsequent frames.
                disableNextControlAnimation = false;
            }
        }


        return (!selectedNavigator || selectedNavigator.canRemoveCurrentView());
    }
    
    /**
     *  @private
     */ 
