Ready for implementation
Magnolia should let me navigate and browse lists (see Definition of terms#list) easily by using either a mouse, a keyboard and using touch gestures.
Description of desired behaviour
A list can be navigated similar to a tree by using the keyboard's UP and DOWN arrow keys. The list shall load additional, previously invisible items on demand to ensure good performance even with large list structures. A visual indicator shows if data is being loaded dynamically.
Likewise, a list may be navigated by using the mouse and the scrollbar. As is the case with keyboard navigation, a clear visual indicator appears if previously hidden items are being loaded and disappears once they become visible.
For touch input, scrolling the list is supported using the common gesture by swiping a single finger up or down.
Note that all scrolling operations should be smooth and not jumpy to avoid loosing sense of where in the list you currently are.
Open and close folder items
Opening folder items in lists
While navigating a list if similar to navigating a tree, handling folder items is actually similar to handling folder items in grids. The difficulty with folder items in lists in Magnolia is that they are actual items, which can also be edited. Since the two primary gestures of mouse and touch are already used to select an item (see Focusing, selecting and opening items#Select a single item) and to open it for editing or inspection (see Focusing, selecting and opening items#Open an item for editing or further inspection), opening a folder item requires using a modifier key for keyboard and mouse input, or the usage of a toolbar or context menu.
Since opening a folder item in a list view can't be done using an intuitive manner easily, Magnolia supports several options. Please refer to the Commands overview in the usage summary for a comprehensive list of navigation commands.
On opening a folder item, the content of the list view is then replaced by the list of items contained in the folder item. If data about items has to be loaded first, the list view is replaced by a visual indicator asking the user for patience. To return to the parent item of a currently shown sub list of items, the list view provides an "up" button - clicking or tapping it returns you to the list view containing the parent folder item.
A list is not a very convenient way to quickly navigate a hierarchical set of items, but has the advantage of visualising the type of a file or even showing thumbnail previews of an item's content.
Magnolia should offer an index, e.g. located next to the scrollbar as we know from current touch devices, for large, sorted lists to allow to quickly jump to a certain position in the list.
Magnolia could offer inertial scrolling as seen of today's touch devices to allow users to quickly navigate large data sets without loosing track of where they are. This would be especially useful on said touch devices, but may actually be a function required to be offered by the browser.
Illustrations, not mockups
The illustrations mainly show which UI elements have to be present in order for the navigation of grids to work. They are presented isolated here, without the context they usually appear in. In the actual mockups e.g. for AdminCentral, some of these elements are actually placed in sidebars, others may remain in the toolbar.