Bug 179931 Provide new interface IStyle to let extension return the style properties values
Provide the IStyle interface to let extension user can return the style property value list for their extension elements.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/elements/strategy/ExtendedItemPropSearchStrategy.java
}
	/**
	 * Gets the property value from some predefined-styles in this extended
	 * item. Such as x-tab header, x-tab footer.
	 * 
	 * @param module
	 * @param extendedItem
	 * @param prop
	 * @return
	 */
	private Object getPropertyFromPredefinedStyles( Module module,
			ExtendedItem extendedItem, ElementPropertyDefn prop )
	{
		IReportItem reportItem = extendedItem.getExtendedElement( );
		try
		{
			if ( reportItem == null )
			{
				extendedItem.initializeReportItem( module );
				reportItem = extendedItem.getExtendedElement( );
			}
		}
		catch ( ExtendedElementException e )
		{
			
		}
		if ( reportItem != null )
		{
			List predefinedStyles = reportItem.getPredefinedStyles( );
			if ( predefinedStyles == null || predefinedStyles.isEmpty( ) )