Bug 193886 NPE is thrown when preview external CSS style in ppt[1205]
engine/org.eclipse.birt.report.engine.emitter.ppt/src/org/eclipse/birt/report/engine/emitter/ppt/PPTRender.java
container.getY( ) ) );
			}
		}
	}
	/**
	 * This method will be invoked while a containerArea ends.
	 * 
	 * @param container
	 *            the ContainerArea specified from layout
	 */
	public void endContainer( IContainerArea container )
	{
		if ( !containerStack.isEmpty( ) )
		{
			containerStack.pop( );
		}
	}
	/**
	 * Creates a new page.
	 * 
	 * @param page
	 *            the PageArea specified from layout
	 */
	protected void newPage( IContainerArea page )
	{
		currentPageNum++;
		currentImageContents.clear( );
		if ( pageWidth <= 0 )
		{
			pageWidth = pptMeasure( page.getWidth( ) );