Bug 135465 [smoke]An error occurred when new a casading Parameter
Description: An error occurred when new a casading Parameter Step to reproduce: 1.new a sample db data source and data set 2.New a cascading parameter group, named "gp1", 3.select the data set, then create two cascading parameters, one is row["customernumber"], named p1; the other is row["customername"] Actual result; error message occurred repeatly
UI/org.eclipse.birt.report.designer.ui/src/org/eclipse/birt/report/designer/ui/dialogs/CascadingParametersDialog.java
| SWT.VIRTUAL );
		previewLable.setText( "" ); 
		previewLable.setLayoutData( new GridData( GridData.FILL_HORIZONTAL ) );
		createLabel( optionsGroup, LABEL_LIST_LIMIT );
		Composite composite = new Composite( optionsGroup, SWT.NULL );
		composite.setLayout( UIUtil.createGridLayoutWithoutMargin( 2, true ) );
		composite.setLayoutData( new GridData( GridData.FILL_HORIZONTAL ) );
		Composite limitArea = new Composite( composite, SWT.NULL );
		limitArea.setLayout( UIUtil.createGridLayoutWithoutMargin( 2, true ) );
		limitArea.setLayoutData( new GridData( GridData.FILL_HORIZONTAL ) );
		listLimit = new Text( limitArea, SWT.BORDER );
		GridData gridData = new GridData( );
		gridData.widthHint = 80;
		listLimit.setLayoutData( gridData );
		listLimit.addVerifyListener( new VerifyListener( ) {
			public void verifyText( VerifyEvent e )
			{
				e.doit = ( "0123456789\0\b\u007f".indexOf( e.character ) != -1 );
			}
		} );
		listLimit.addModifyListener( new ModifyListener( ) {
			private String oldValue = ""; 
			public void modifyText( ModifyEvent e )
			{
				try
				{
					if ( !StringUtil.isBlank( listLimit.getText( ) ) )
					{
						Integer.parseInt( listLimit.getText( ) );
						oldValue = listLimit.getText( );