Client-side Ajax check is not triggered for a required custom control
A field of custom control is added into a section and is set as Required.
Unlike a standard control set as Required, the "Value cannot be blank" error message is not shown bellow the field when the field is left blank and focus gets out of the field.
We know if we add a Validate rule, the required message can be dispalyed on the Harness's error page, which, nevertheless, is not our required hehavior.