I guess this is due to the fact, that the actual heigth of the form is initially calculated during the loading of the form. If you later on remove/ elements from the DOM the size of the form is not re-calculated.

Thanks

I moved  NWF$("#s4-ribbonrow").hide(); to NWF$(document).ready(function() function

Before it was in NWF.FormFiller.Events.RegisterAfterReady(function()

It is fine now,

There should actually be a javascript-function the trigger a re-calc of the heights ... but I can't seem to remember the actual name.