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
ExceptionHandler.handle( e );
			return;
		}
		refreshValueTable( );
		index--;
		if ( index < 0 && valueTable.getTable( ).getItemCount( ) > 1 )
		{
			index = 0;
		}
		StructuredSelection selection = null;
		if ( index != -1 )
		{
			selection = new StructuredSelection( valueTable.getTable( )
					.getItem( index )
					.getData( ) );
		}
		else
		{
			selection = StructuredSelection.EMPTY;
		}
		valueTable.setSelection( selection );
	}
	private String[] getDataSetColumns( ScalarParameterHandle handle,
			boolean needFilter )
	{
		DataSetHandle dataSet = getDataSet( handle );
		if ( dataSet == null )
		{
			return new String[0];
		}