Bug 153523 OK button in parameter dialog is enabled without default value in combo-box
Description: OK button in parameter dialog is enabled without default value in combo-box Steps to reproduce: 1. New a report parameter, combo-box. 2. Click New button, input abc as value, click OK 3. Set abc as default value and close Edit Parameter dialog. 4. New a data source and dataset 5. Edit the parameter, remove abc value and import values from dataset Expected result: OK button is disabled for there is no default value. Actual result: OK button is enabled.
UI/org.eclipse.birt.report.designer.ui/src/org/eclipse/birt/report/designer/ui/dialogs/CascadingParametersDialog.java
valueTable.setContentProvider( contentProvider );
		valueTable.setLabelProvider( labelProvider );
		valueTable.setCellModifier( cellModifier );
		valueTable.addSelectionChangedListener( new ISelectionChangedListener( ) {
			public void selectionChanged( SelectionChangedEvent event )
			{
				ISelection selection = event.getSelection( );
				Object param = ( (StructuredSelection) selection ).getFirstElement( );
				if ( param != selectedParameter )
				{
					if ( param instanceof ScalarParameterHandle )
					{
						try
						{
							saveParameterProperties( );
							selectedParameter = (ScalarParameterHandle) param;
						}
						catch ( SemanticException e )
						{
							ExceptionHandler.handle( e );
							valueTable.setSelection( new StructuredSelection( selectedParameter ) );
						}
						refreshParameterProperties( );
						updateButtons( );
					}
				}
			}
		} );
	}
	private void createPropertiesPart( Composite parent )