src/main/java/org/efaps/ui/wicket/components/values/DropDownField.java
private void addBehaviors()
    {
        if (this.uiField.getFieldConfiguration().getField().hasEvents(EventType.UI_FIELD_UPDATE)) {
            final List<EventDefinition> events =
                            this.uiField.getFieldConfiguration().getField().getEvents(EventType.UI_FIELD_UPDATE);
            String eventName = "change";
            for (final EventDefinition event : events) {
                eventName = event.getProperty("Event") == null ? "change" : event.getProperty("Event");
            }
            add(new AjaxFieldUpdateBehavior(eventName, Model.of(this.uiField), false) {

                /** The Constant serialVersionUID. */
                private static final long serialVersionUID = 1L;

                @Override
                protected void onSubmit(final AjaxRequestTarget _target)
                {
                    // add the previous value as a parameter
                    final DropDownOption option = (DropDownOption) getDefaultModelObject();
                    try {
                        if (option != null) {
                            Context.getThreadContext().getParameters().put(
                                            getFieldConfig().getName() + "_eFapsPrevious",
                                            new String[] { option.getValue() });
                        }
                    } catch (final EFapsException e) {
                        DropDownField.LOG.error("EFapsException", e);
                    }
                    super.onSubmit(_target);
                    DropDownField.this.converted = false;
                    updateModel();
                    DropDownField.this.converted = false;
                }
            });
        }
        add(new AttributeAppender("style", "text-align:" + getFieldConfig().getAlign(), ";"));
        // add the width only if not in a table
        if (getFieldConfig().hasProperty(UIFormFieldProperty.WIDTH) && !getFieldConfig().isTableField()) {
            add(new AttributeAppender("style", "width:" + getFieldConfig().getWidth(), ";"));
        }
    }
private void addBehaviors()
    {
        if (this.uiField.getFieldConfiguration().getField().hasEvents(EventType.UI_FIELD_UPDATE)) {
            final List<EventDefinition> events =
                            this.uiField.getFieldConfiguration().getField().getEvents(EventType.UI_FIELD_UPDATE);
            String eventName = "change";
            for (final EventDefinition event : events) {
                eventName = event.getProperty("Event") == null ? "change" : event.getProperty("Event");
            }
            add(new AjaxFieldUpdateBehavior(eventName, Model.of(this.uiField), false) {

                /** The Constant serialVersionUID. */
                private static final long serialVersionUID = 1L;

                @Override
                protected void onSubmit(final AjaxRequestTarget _target)
                {
                    // add the previous value as a parameter
                    final DropDownOption option = (DropDownOption) getDefaultModelObject();
                    try {
                        if (option != null) {
                            Context.getThreadContext().getParameters().put(
                                            getFieldConfig().getName() + "_eFapsPrevious",
                                            new String[] { option.getValue() });
                        }
                    } catch (final EFapsException e) {
                        DropDownField.LOG.error("EFapsException", e);
                    }
                    super.onSubmit(_target);
                    DropDownField.this.converted = false;
                    updateModel();
                    DropDownField.this.converted = false;
                }
            });
        }
        add(new AttributeAppender("style", "text-align:" + getFieldConfig().getAlign(), ";"));
        // add the width only if not in a table
        if (getFieldConfig().hasProperty(UIFormFieldProperty.WIDTH) && !getFieldConfig().isTableField()) {
            add(new AttributeAppender("style", "width:" + getFieldConfig().getWidth(), ";"));
        }
    }
Adds the behaviors.