A tree view is a popular and useful graphical method for displaying on a display screen the hierarchical organization of objects, such as files, in computer memory. A tree view takes its name from an analogy to trees in nature, which have a hierarchical organization of branches and leaves. For example, a leaf belongs to a small branch, which further belongs to a large branch, and all branches of the tree have a common starting point at the root.
Analogously, objects in computer memory can have a hierarchical organization, in that an object can be contained in a sub-directory, which can be further contained in another directory, and so on. Thus, all of computer memory can be divided up into sub-directories and directories that ultimately are all contained in a root directory. The structure of the displayed tree view shows both nesting of objects and where the objects belong within the nested hierarchical organization.
Unfortunately, such tree views can become cumbersome when the list of objects is large. It might take several scrolling operations by the user to page through a large tree before finding a desired object, and the user can easily become lost. Thus, one of the biggest advantages of a tree display--that the user has an orientation to where the objects are located--can become confusing when there are too many objects.
Prior file managers attempted to address this problem by providing the function of taking infrequently used objects at a displayed, expanded level of the tree and un-expanding (collapsing) them into a visual set, leaving the visual set in its respective position. This allowed the user to see more of the important information, without totally removing the objects, thus preserving the advantages of a tree view. In prior file managers, an entire branch of the tree is shown in its expanded form or hidden in its collapsed form. The branch of the tree is often a directory or subdirectory, and the name that the file manager often associates with the collapsed form is the name of the directory or subdirectory that contains the collapsed (unexpanded) objects.
Prior file managers suffer from the problem that they could only expand and collapse entire branches. Although this works well when a branch had a small number of objects, as the number of objects in a branch increases, it becomes increasingly difficult for the user to find a desired object and maintain an orientation within the tree.