There should be a way to toggle visibility of elements in OE. In the element explorer for example have a little 'eye' or something like photoshop layers have.
Or if the 'visibility' property for elements toggled the element (and it's children) in OE.

as of 1.44 I can't make something invisible in OE until I preview it in a browser.
I think this can be a good feature if you have overlapping content for areas that either code changes the visibility of each section or if fixed elements and other elements are initially overlapping in OE. This will allow the user to update the content underneath easier.