You can set the point at which
validation occurs—when the user clicks outside the widget, as the
user makes selections, or when the user tries to submit the form.
Select a Validation Checkbox widget in the Document
window.
In the Property inspector (Window > Properties),
select the option that indicates when you want validation to occur.
You can select all of the options or none of them.
Blur
Validates whenever the user clicks outside the check box.