Expand/collapse buttons are optional buttons displayed on the tree lines (see ButtonStyle and Items.TreeLineStyle) to allow users to expand and collapse tree sections by clicking a button.  The button graphics can be modified using the ButtonAppearance property and are shared between all items.  Items on level 0 (the highest level or root level) have special level 0 expand/collapse buttons which can be enabled separately, but share the same graphics.

Expand/collapse buttons for individual items can be suppressed using the Item.HideExpandCollapseButton property.

Tree Components