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Description of desired behaviour
A tree list can be navigated by using the keyboard's arrow keys (UP, RIGHT, LEFT and DOWN arrow keys). The tree list shall load additional, previously invisible items on demand to ensure good performance even with large tree structures. A visual indicator shows if data is being loaded dynamically.
Likewise, a tree 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.
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Note that all scrolling operations should be smooth and not jumpy to avoid loosing sense of where in the list you currently are.
Expand and collapse folder items
. Note that list shall only scroll up and down. We don't plan to support left and right scrolling for lists, since this is a feature often not noticed by users.
Open and close folder items
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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 Focussing and selecting items) and to open it for editing or inspection (see Focussing and selecting items), opening a folder item requires using a modifier key for all input methods. |
Folder items in lists may be opened or closed by double-A folder item is a regular item, which - in addition to providing the tasks defined by its type - contains other items. Folder items may be expanded or collapsed by clicking on or touching an expand/collapse visual indicator displayed right next to an item's icon. The indicator clearly shows, if its item is expanded to show the next level of items, or collapsed, hiding all its sub items. If a folder item is expanded, only the next level of its sub items is shown. If data about items has to be loaded first, a visual indicator asks the user for patience. Clicking on or touching an expanded folder item collapses it again and hides all of its sub items.Folder items can also be expanded by hitting the RIGHT arrow key (LEFT on RTL installations) while the keyboard focus is on a collapsed folder item (nothing happens, if the folder item is open already). To collapse a folder item again, hit the LEFT arrow key (RIGHT on RTL installations) with the keyboard focus either on the folder item you intend to collapse or any of its sub items on the next level only.
Using the arrow keys presents a very efficient way to navigate a tree. It will quickly become one major way to work with trees for any experienced user. Care must be taken therefore to ensure that this will be a smooth, reliable, complete and non-irritating experience.
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