TYPO3 Core

Could you elaborate on the feature request a bit more?

Viewports are more a thing of the frontend output, if I understand your intention correctly. Thus, you would need to use CSS viewport indicators to show/hide content. To specify, which content should be hidden or not, you could for example:

• Create a custom backend layout and create columns per viewport, then in the frontend output use CSS to access these specific columns
• Create/use a tt_content column to indicate viewport relation, so that in the frontend fluid you can attach CSS classes and show/hide them in different viewports

If I completely misunderstood your intent, I'd be curious to know more about your idea! :-)