I've created a form with plenty of text, a couple of radio buttons and two text fields on the bottom of the form. When testing the form, the cursor will appear in the first text field, which causes the form to open near the bottom of the form, instead of opening at the top.
How can I force the form to always open at the top?
In most cases, focusing in the first control is what's best for users, but there are indeed cases, like the one you describe, where this isn't desirable. In cases like this, I'd recommend you use the oxf.fr.detail.initial-focus.*.* to disable this feature. And note that this propery allows you to disable setting the focus just for just a specific form or group of form, and keep it for other forms.