Make the hide sidebar button in flyouts availabe at larger screen sizes

[brianrivet-tilt]

When using flyouts to manage content the sidebar of the entry being edited can be hidden with a button at smaller screen sizes, but above a certain size the button goes away and the sidebar is always visible. However at some browser sizes this actually causes you to have less screen space for the actual editing controls even though the screen size is larger. It might be better to have the hide sidebar button be available at all sizes so that the sidebar can be hidden when not needed regardless of the screen size.