Move away from document.write, that would not reset the javascript environment of the document with many side effects and reimplement the fullscreen preview using an iframe
- name the formfield consistently with its ancestry - provide two preview and visualization styles: inline, where the page is displayed alongside the code and in an own window, opened by clicking on a button - allow to customize whether one prefers the inline style preview, the window preview or none via the preview_inline and preview_window parameters - fix visualization when formfield is rendered as readonly and no monaco editor is available - localize button text