package
{
	import mx.containers.Canvas;
	import mx.core.ScrollPolicy;
	import mx.events.FlexEvent;

	public class ResizeScrollingCanvas extends Canvas
	{
		public function ResizeScrollingCanvas()
		{
			super();
			
			addEventListener(FlexEvent.UPDATE_COMPLETE, updateCompleteHandler);
		}
		
		protected var hadScrollBar : Boolean;
		protected var oldVerticalScrollPolicy : String; 
		
		protected function updateCompleteHandler(event : FlexEvent) : void {
			
			var hasScrollBar : Boolean = (this.verticalScrollBar != null);
			
			trace("updateDisplayList before / after = " + hadScrollBar + " / " + hasScrollBar + " scrollbar = " + verticalScrollBar + " policy = " + verticalScrollPolicy);
			
			if (verticalScrollBar != null) 
				trace("min = " + verticalScrollBar.minScrollPosition + ", max = " + verticalScrollBar.maxScrollPosition);
			
			if (hasScrollBar && verticalScrollBar.maxScrollPosition == 0) {

				//Remove scrollbar
				verticalScrollPolicy = oldVerticalScrollPolicy;
				trace("Off! policy = " + verticalScrollPolicy + ", oldPolicy = " + oldVerticalScrollPolicy);
			}
			
			//Change?
			if(hasScrollBar != hadScrollBar) {
				//Changed! From off to on?
				trace("Changed!");
				
				if (hasScrollBar) {
					
					oldVerticalScrollPolicy = (this.verticalScrollPolicy == ScrollPolicy.ON) ? ScrollPolicy.ON : ScrollPolicy.AUTO;
					verticalScrollPolicy = ScrollPolicy.ON;
					
					trace("On! policy = " + verticalScrollPolicy + ", oldPolicy = " + oldVerticalScrollPolicy);
					
				}
				
				//Force redraw. Needed?
				invalidateDisplayList();
			}
			
			hadScrollBar = (verticalScrollBar != null);
		}
		
	}
}