Bug 198839 Hide element on master page works only for PDF output
1. Insert any element (grid, label, image, text) in the header or footer of the master page. 2. Use the Visibility property to hide the element for all outputs. Expected result: Element does not appear in any of the output formats. Actual result: The element is hidden only in PDF.
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/api/impl/EngineTask.java
* Engine task type. for usage in BIRT scripting.
	 */
	protected int taskType = IEngineTask.TASK_UNKNOWN;
	/**
	 * @param engine
	 *            reference to report engine
	 * @param appContext
	 *            a user-defined object that capsulates the context for running
	 *            a task. The context object is passed to callback functions
	 *            (i.e., functions in image handlers, action handlers, etc. )
	 *            that are written by those who embeds engine in their
	 *            applications
	 */
	protected EngineTask( IReportEngine engine, IReportRunnable runnable )
	{
		taskID = id++;
		this.engine = engine;
		this.log = engine.getLogger( );
		
		executionContext = new ExecutionContext( this );
		
		executionContext.setReportContext( new ReportContextImpl(
				executionContext ) );
		setReportRunnable( runnable );
		
		executionContext.setAppContext( engine.getConfig( ).getAppContext( ) );
		cancelFlag = false;
		runningStatus = STATUS_NOT_STARTED;
	}
	protected EngineTask( IReportEngine engine, IReportRunnable runnable,