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
{
				if ( event.data instanceof String
						&& !event.data.equals( "null" ) )
					insertText( (String) event.data );
			}
		} );
	}
	/**
	 * Insert a text string into the text area
	 * 
	 * @param text
	 */
	private void insertText( String text )
	{
		if ( text == null )
			return;
		StyledText textWidget = viewer.getTextWidget( );
		int selectionStart = textWidget.getSelection( ).x;
		textWidget.insert( text );
		textWidget.setSelection( selectionStart + text.length( ) );
		textWidget.setFocus( );
	}
	/**
	 * Creates the textual query editor 
	 * @param parent
	 */
	private void createTextualQueryComposite( Composite parent )
	{
		Composite composite = new Composite( parent, SWT.FILL
				| SWT.LEFT_TO_RIGHT );