Trees

A tree control allows the user to inspect, manipulate or select from a hierarchichal list of items. Trees may have one or more columns, and contain text, graphics, simple controls, or a combination of all three.

[Tip]Use trees with care!

Because of their complexity compared to other controls, novice and some intermediate users often have problems using and understanding tree controls. If your application is designed for that type of user, you might want to consider alternative ways of presenting the information, such as the Nautilus list or icon view, or the hierarchical browser lists found in GNUstep's File Viewer.

Figure 6.21. A simple tree control with one level of hierarchy

Picture of tree control showing months of the year as top
          level nodes, and public holidays in those months as their children

Guidelines

Sortable Trees

As with lists, the user may find it useful to sort long or multi-column trees. See the guidelines in the section called “Sortable Lists” for more information.