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A unit may either use a single-state or a two-state interface. If a unit can provide a short overview of its core settings, but needs more space to show all values, it is dubbed an expanding unit and uses the two-state interface offering both a collapsed and an expanded view. In the expanded view, the unit takes over most of the space available in the rack and thus has plenty of space available to show its data. In the collapsed view, only the brief overview fits in. If a unit only needs one interface to show its settings, it is called a uniform unit and uses a single-state interface offering only the collapsed view.
Same unit and view, different page
If a user chooses to show the page options, then moves to a different page, the page options of that page are displayed as well. The same holds true if a user expands a particular unit to show a specific aspect of the page. By surfing to a different page, he gets the same aspect of the page he just surfed to.
This is an important concept: in order to check one particular aspect of a set of pages, a user chooses the unit providing it, chooses the collapsed or expanded view, if available, then surfs to all pages.
The toolbar unit
The toolbar is a special unit hosting two global functions, namely the clipboard and global undo/redo. In particular undo/redo needs to be available at any time and independent of the currently selected content element. The toolbar thus is available at all times and at the exact same location. It even remains visible if a unit is switched to show its expanded view.
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