In the full-screen preview:

• We hide all bars by default:
  • we only offer a button to show the Action bar,
  • and a button to reveal all hidden interface elements.

• The Action bar is hidden by default.

The resulting interface puts a focus on pixel-perfect rendering in the current resolution and only shows two UI elements, floating on top of content: one for leaving the full-screen view, one for showing (and hiding) the rest of the UI. This focus allows to view the page very close to how it will actually render in the current browser window's resolution, which is going to be sufficient in most day-to-day editing cases. You can even take this one step further to get a preview of the real rendering without any obstructions and UI elements.

If a user explicitly asks for the UI to become visible (e.g. to get access to the switchers to choose a particular variant, or to see the current page's status), its elements all cover the content he's previewing: all bars are shown floating on top and the Action bar is shown in its extended view.

As is the case with the "Preview as visitor" app, if you collapse the Action bar, we'll hide it away entirely. If you expand the Action bar, it floats on top of content.