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
GridData gd = new GridData( GridData.FILL_HORIZONTAL );
		gd.horizontalSpan = 2;
		schemaCombo.setLayoutData( gd );
		enableSchemaComponent( isSchemaSupported );
		Label FilterLabel = new Label( selectTableGroup, SWT.LEFT );
		FilterLabel.setText( JdbcPlugin.getResourceString( "tablepage.label.filter" ) );
		searchTxt = new Text( selectTableGroup, SWT.BORDER );
		{
			GridData data = new GridData( GridData.FILL_HORIZONTAL );
			data.horizontalSpan = 2;
			searchTxt.setLayoutData( data );
		}
		
		Label selectTypeLabel = new Label( selectTableGroup, SWT.NONE );
		selectTypeLabel.setText( JdbcPlugin.getResourceString( "tablepage.label.selecttype" ) );
		
		filterComboViewer = new ComboViewer( selectTableGroup, SWT.READ_ONLY );
		setFilterComboContents( filterComboViewer );
		filterComboViewer.getControl( )
				.setLayoutData( new GridData( GridData.FILL_HORIZONTAL ) );
		
		Button findButton = new Button( selectTableGroup, SWT.NONE );
		findButton.setText( JdbcPlugin.getResourceString( "tablepage.button.filter" ) );
		
		findButton.addSelectionListener( new SelectionAdapter( ) {
			public void widgetSelected( SelectionEvent event )
			{
				PlatformUI.getWorkbench( )
						.getDisplay( )