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
}
	/**
	 * Draws background image for the container.
	 * 
	 * @param containerStyle
	 *            the style of the container we draw background image for
	 * @param startX
	 *            the absolute horizontal position of the container
	 * @param startY
	 *            the absolute vertical position of the container
	 * @param width
	 *            container width
	 * @param height
	 *            container height
	 */
	private void drawBackgroundImage( IStyle containerStyle, double startX,
			double startY, double width, double height )
	{
		String bi = PropertyUtil.getBackgroundImage( containerStyle.getProperty( StyleConstants.STYLE_BACKGROUND_IMAGE ) );
		if ( bi == null )
		{
			return;
		}