There is a fullscreen mode that prints a window over the full size of the screen without showing toolbars/navigation/extensions... Is there a "full window" mode that do the same, but over the full size of a window? It would be a simple webview in a system window but without the control toolbars. It would be very useful when tiling several Firefox windows without wasting space for toolbars/tabs... This mode should be specific for a window since I do not want to loose the controls on the main screen-wide window.

[attached image is a sketch of what I'm looking for]