public String popup(PopupField field) {
if (field == this.outputActivationField) {
ActivationDialog dialog = new ActivationDialog(EncogWorkBench
.getInstance().getMainWindow());
dialog.setActivation(this.outputActivationFunction);
if (!dialog.process())
return null;
else {
this.outputActivationFunction = dialog.getActivation();
return dialog.getActivation().getClass().getSimpleName();
}