iFuntastic displays your widgets on the Widgetation page. It submits the web page to a background process for rendering, then displays the resulting image. This means that it cannot display animations properly since it does not evaluate conditions repeatedly. It also means that changes that happen through conditions or built-in HTML functions are not reflected in the bounding boxes of the widgets in the UI.

To at least see running animations you can choose to send the web page to Safari for a live preview. This option is in the View menu on the Widgetation page.

A large monitor (or a second one) will make things considerably more comfortable too.