Bug 199021 Error message pops up several times when click an invalid dataset
Description: There is a sqlserver datasource and dataset, remove the jtds driver to let the dataset invalid. Double click on the dataset, the error message will pop up serveral times. Build version:2.2.0.v20070807-0630 Steps to reproduce: 1. Create a sqlserver datasource and dataset. 2. Remove the jtds driver, and the dataset will be invalid. 3. Double click on the dataset. Expect result: Error message pops up once to indicate the problem. Actual result: Error message pops up serveral times.
data/org.eclipse.birt.report.data.oda.jdbc.ui/src/org/eclipse/birt/report/data/oda/jdbc/ui/editors/SQLDataSetEditorPage.java
private TreeItem[] selectionMac = null;
	private boolean isSchemaSupported = false;
	private boolean expandDbObjectsTree = false;
	private IMetaDataProvider metaDataProvider = null;
	private JdbcSQLSourceViewerConfiguration sourceViewerConfiguration = null;
	private String cachedSearchTxt = "";
	private String formerQueryTxt = "";
	private String cachedDbType = "";
	private int cachedSchemaComboIndex = -1;
	private DataSourceDesign prevDataSourceDesign;
	private DataSetDesign dataSetDesign;
	private boolean shouldUpdateDataSetDesign;
	
	protected ArrayList schemaList;
	 
	protected ArrayList tableList;
	private Connection jdbcConnection = null;
	private static String TABLE_ICON = "org.eclipse.birt.report.data.oda.jdbc.ui.editors.SQLDataSetEditorPage.TableIcon";
	private static String VIEW_ICON = "org.eclipse.birt.report.data.oda.jdbc.ui.editors.SQLDataSetEditorPage.ViewIcon";
	private static String PAGE_ICON = "org.eclipse.birt.report.data.oda.jdbc.ui.editors.SQLDataSetEditorPage.PageIcon";
	private static String SCHEMA_ICON = "org.eclipse.birt.report.data.oda.jdbc.ui.editors.SQLDataSetEditorPage.SchemaIcon";
	private static String DATABASE_ICON = "org.eclipse.birt.report.data.oda.jdbc.ui.editors.SQLDataSetEditorPage.DbIcon";
	private static String COLUMN_ICON = "org.eclipse.birt.report.data.oda.jdbc.ui.editors.SQLDataSetEditorPage.ColumnIcon";
	private static String DEFAULT_MESSAGE = JdbcPlugin.getResourceString( "dataset.new.query" );	
	
	private static String ENABLED = "YES";
	
	private static boolean isPageInitialization = true;
	private static Logger logger = Logger.getLogger( SQLDataSetEditorPage.class.getName( ) );