Bug 123174 inappropriate column header when inserting a table group
steps to reproduce: - create a table, bind it to an existing data set - insert a table group, e.g. row["CUSTOMERNUMBER"] - drag some data into table detail row - preview report expected behavior: - the column header should be the name of the column actual behavior: - the column header was expr. row["CUSTOMERNUMBER"]
UI/org.eclipse.birt.report.designer.ui/src/org/eclipse/birt/report/designer/ui/dialogs/GroupDialog.java
*            the parent composite
	 */
	private void createFieldArea( Composite parent )
	{
		Composite composite = new Composite( parent, SWT.NONE );
		composite.setLayout( new GridLayout( ) );
		GridData gd = new GridData( GridData.FILL_BOTH );
		gd.widthHint = 200;
		composite.setLayoutData( gd );
		
		new Label( composite, SWT.NONE ).setText( GROUP_DLG_GROUP_NAME_LABEL );
		
		nameEditor = new Text( composite, SWT.SINGLE | SWT.BORDER );
		nameEditor.setLayoutData( new GridData( GridData.FILL_HORIZONTAL ) );
		
		new Label( composite, SWT.NONE ).setText( GROUP_DLG_GROUP_KEY_LABEL );
		
		Composite keyArea = new Composite( composite, SWT.NONE );
		keyArea.setLayoutData( new GridData( GridData.FILL_HORIZONTAL ) );
		keyArea.setLayout( UIUtil.createGridLayoutWithoutMargin( 2, false ) );
		keyChooser = new Combo( keyArea, SWT.DROP_DOWN );
		keyChooser.setLayoutData( new GridData( GridData.FILL_HORIZONTAL ) );
		Button exprButton = new Button( keyArea, SWT.PUSH );
		exprButton.setText( "..." ); 
		exprButton.addSelectionListener( new SelectionAdapter( ) {
			public void widgetSelected( SelectionEvent event )
			{
				ExpressionBuilder expressionBuilder = new ExpressionBuilder( getKeyExpression( ) );
				expressionBuilder.setExpressionProvier( new ExpressionProvider( dataSetList ) );
				if ( expressionBuilder.open( ) == OK )