Bug 161191 Null is inserted when drag columns to query text with ctrl key pressed
Description: Null is inserted when drag columns to query text with ctrl key pressed Steps to reproduce: 1. New a data source. 2. New a dataset. 3. Press and hold ctrl key, select OFFICECODE and CITY columns, drag to query text. Expected result: "CLASSICMODELS.OFFICES.OFFICECODE,CLASSICMODELS.OFFICES.CITY" is inserted in query text. Actual result: "null,CLASSICMODELS.OFFICES.OFFICECODE,CLASSICMODELS.OFFICES.CITY" is inserted
data/org.eclipse.birt.report.data.oda.jdbc.ui/src/org/eclipse/birt/report/data/oda/jdbc/ui/editors/SQLDataSetEditorPage.java
CompositeRuler ruler = new CompositeRuler( );
		LineNumberRulerColumn lineNumbers = new LineNumberRulerColumn( );
		ruler.addDecorator( 0, lineNumbers );
		viewer = new SourceViewer( composite, ruler, SWT.H_SCROLL
				| SWT.V_SCROLL );
		sourceViewerConfiguration = new JdbcSQLSourceViewerConfiguration( this.getDataSetDesign( ) );
		viewer.configure( sourceViewerConfiguration );
		
		doc = new Document( getQueryText() );
		FastPartitioner partitioner = new FastPartitioner( new SQLPartitionScanner( ),
				new String[]{
						SQLPartitionScanner.SINGLE_LINE_COMMENT1,
						SQLPartitionScanner.SINGLE_LINE_COMMENT2,
						SQLPartitionScanner.MULTI_LINE_COMMENT,
						IDocument.DEFAULT_CONTENT_TYPE
				} );
		partitioner.connect( doc );
		doc.setDocumentPartitioner( partitioner );
		viewer.setDocument( doc );
		viewer.getTextWidget( ).setFont( JFaceResources.getTextFont( ) );
		viewer.getTextWidget( )
				.addBidiSegmentListener( new BidiSegmentListener( ) {
					/*
					 * @see org.eclipse.swt.custom.BidiSegmentListener#lineGetSegments(org.eclipse.swt.custom.BidiSegmentEvent)
					 */
					public void lineGetSegments( BidiSegmentEvent event )
					{
						event.segments = SQLUtility.getBidiLineSegments( event.lineText );
					}