If the <listbox> tag is a blend of <grid> and <menulist> concepts, then the <tree> tag is a blend of <listbox> and <iframe>. A <tree> widget is a vertically arranged, scrollable set of records like <listbox>. <tree> allows a simple containment hierarchy to be imposed on the displayed rows so that rows are indented different amounts and decorated with graphical hints. When this hierarchy is not imposed, <tree> looks much like <listbox>.
<tree> gives the user room to control the display of the records presented. The user can collapse and expand subparts of the tree interactively. Columns can be reordered, hidden, and resized, and their contents can be sorted and selected.
<tree> gives the application programmer many data processing ...