Bug 141959 Changing data set didn't clean old column bindings
Steps to reproduce: 1.Add two data sets, "ds1" and "ds2" 2.Add a table, binding with "ds1". All "ds1" column bindings generate automatically, that's good 3.Change "ds1" to None Expected result: All "ds1" column bindings should be cleaned Actual result: All "ds1" column bindings are still there. If changing to "ds2", "ds2" column bindings will be added after them.
UI/org.eclipse.birt.report.designer.ui/src/org/eclipse/birt/report/designer/ui/dialogs/ColumnBindingDialog.java
public static final String DEFAULT_DLG_TITLE = Messages.getString( "ColumnBindingDialog.DialogTitle" ); 
	private static final String NONE = Messages.getString( "BindingPage.None" );
	private static final String LABEL_COLUMN_BINDINGS = Messages.getString( "ColumnBindingDialog.Label.DataSet" ); 
	private static final String WARN_COLUMN_BINDINGS = Messages.getString( "ColumnBingingDialog.Label.Warn" ); 
	
	
	private static final String COLUMN_NAME = Messages.getString( "ColumnBindingDialog.Column.Name" ); 
	private static final String COLUMN_DATATYPE = Messages.getString( "ColumnBindingDialog.Column.DataType" ); 
	private static final String COLUMN_EXPRESSION = Messages.getString( "ColumnBindingDialog.Column.Expression" ); 
	private static final String COLUMN_AGGREGATEON = Messages.getString( "ColumnBindingDialog.Column.AggregateOn" ); 
	private static final String INPUT_PROPMT = Messages.getString( "ColumnBindingDialog.InputPrompt" ); 
	private static final IChoiceSet dataTypeChoiceSet = DesignEngine.getMetaDataDictionary( )
			.getChoiceSet( DesignChoiceConstants.CHOICE_COLUMN_DATA_TYPE );
	private static final IChoice[] dataTypes = dataTypeChoiceSet.getChoices( null );
	private static final String[] dataTypeDisplayNames = ChoiceSetFactory.getDisplayNamefromChoiceSet( dataTypeChoiceSet );
	private boolean canSelect = false;
	private ReportItemHandle inputElement;
	
	
	private TableViewer bindingTable;
	private ExpressionCellEditor expressionCellEditor;
	private String selectedColumnName = null;
	private IStructuredContentProvider contentProvider = new IStructuredContentProvider( ) {
		public void dispose( )
		{
		}
		public void inputChanged( Viewer viewer, Object oldInput,
				Object newInput )
		{
		}