private void operatorChanged(OperatorSelection selection) {
parametersContainer.clear();
String operator = selection.getValue();
if ( SuggestionCompletionEngine.isCEPWindowOperatorTime( operator ) ) {
AbstractRestrictedEntryTextBox txt = new CEPTimeParameterTextBox( hcw.getWindow(),
1 );
initialiseTextBox( txt );
} else if ( SuggestionCompletionEngine.isCEPWindowOperatorLength( operator ) ) {
AbstractRestrictedEntryTextBox txt = new CEPLengthParameterTextBox( hcw.getWindow(),
1 );
initialiseTextBox( txt );
} else {
parametersContainer.setVisible( false );
hcw.getWindow().clearParameters();