Bug 136241 [regression]Preview template in web viewer and pdf didn't get correct effect.
Description: Preview template items in web viewer and pdf didn't get correct effect. Steps to reproduce: 1. Create template items. 2. Preview in Web Viewer and pdf. Expected result: Same effect as in html. Actual result: In web viewer, see only blank box. In pdf, blank page.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/core/DesignElement.java
public StyleElement getStyle( Module module )
	{
		return null;
	}
	/**
	 * Returns the shared style referenced by this element. This method will not
	 * try to resolve the style element if the value is un-resolved.
	 * <p>
	 * Part of: Style system.
	 * 
	 * @return the shared style, or null if this element does not explicitly
	 *         reference a shared style, or the value is un-resolved
	 */
	public StyleElement getStyle( )
	{
		return null;
	}
	/**
	 * Caches an element that derives from this element.
	 * <p>
	 * Part of: Inheritance system.
	 * 
	 * @param child
	 *            The new derived element.
	 */
	protected void addDerived( DesignElement child )
	{
		if ( derived == null )
			derived = new ArrayList( );
		assert child != null;