Bug 178519 Problems in multi-rows header
Please see the attachments.
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/layout/pdf/PDFBlockStackingLM.java
{
		protected CompositeArea cache = new CompositeArea();
		
		protected int maxHeight = 0;
		
		public KeepWithMgr()
		{
			
		}
		
		public KeepWithMgr(int maxHeight)
		{
			this.maxHeight = maxHeight;
		}