Bug 209119 Need WebViewer provide cancel function
Need WebViewer provide a cancel function, this will be used to cancel current report execution during designer preview.
viewer/org.eclipse.birt.report.viewer/src/org/eclipse/birt/report/viewer/utilities/WebViewer.java
{
				String option = options[i];
				if ( pattern.matcher( option ).matches( ) )
				{
					rtl = true;
					break;
				}
			}
		}
		if ( "true".equalsIgnoreCase( svgFlag ) ) 
		{
			bSVGFlag = true;
		}
		String masterPageContent = ViewerPlugin.getDefault( )
				.getPluginPreferences( ).getString( MASTER_PAGE_CONTENT );
		boolean bMasterPageContent = true;
		if ( "false".equalsIgnoreCase( masterPageContent ) ) 
		{
			bMasterPageContent = false;
		}
		
		String encodedResourceFolder = null;
		try
		{
			if ( resourceFolder != null )
				encodedResourceFolder = URLEncoder.encode( resourceFolder,
						"utf-8" ); 
		}
		catch ( UnsupportedEncodingException e )
		{