As of newest nightly, ion-content now adds the has-{anything} classes dynamically and you don’t have to manage it yourself at all.
That means even if you put an ng-if around a header bar, when it’s added/removed the content will fix itself.
Just one of the many nice things coming very soon for 1.0 beta =)
We are moving very fast and breaking many things - we realize we need to have a very flexible, intuitive, and robust API before 1.0. And many things did need change for that to happen.
It should ship very soon™.