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
/**
	 * 
	 * @param event
	 */
	private void populateEventData( TypedEvent event )
	{
		TreeItem[] selection = availableDbObjectsTree.getSelection( );
		
		if ( selection == null || selection.length == 0 )
			selection = selectionMac;
		String identifierQuoteString;
		try
		{
			identifierQuoteString = metaDataProvider.getMetaData( )
					.getIdentifierQuoteString( );
		}
		catch ( SQLException e )
		{
			identifierQuoteString = "";
		}
		if ( selection.length > 0 )
		{
			String data = "";
			for ( int i = 0; i < selection.length; i++ )
			{
				Object obj = selection[i].getData( );
				
				if ( obj instanceof DbObject )
				{
					if ( ( (DbObject) obj ).getType( ) != DbObject.PROCEDURE_TYPE )