Updated March 5, 2015
In order to set up the fail safe, use whatever you would use if InGo was not installed, and target the Activator Widget to that element. For example, if you would normally do a link:
<a href="registrar/url"class="registration-button">Register Here</a>
then you would target the .registration-button with the ingoWidget invocation:
$(".registration-button").ingoWidget(...)
Likewise, if it would be a form if InGo was not installed you would instead target the form.
For example, given the following form:
<formclass="registration-form-step-1"action="registration/step/2">
<label>Email: <inputname="email"></label>
<label>FirstName: <inputname="firstName"></label>
<button>Register Now</button>
</form>You could target the form using:
$(".registration-form-step-1").ingoWidget(...)
Note that we are targeting the form here, not the button. When the widget loads it will replace the form (as it would replace the link in the first example). That means that if the widget fails to load, the user will still be able to register.
A popup works the same way, except the user-experience is less than desirable to have it target a form since you would click on the form and have a popup show when InGo is working, which is confusing for the end user. So it should target a link.