Expand/collapse buttons are optional buttons displayed to allow users to expand and collapse tree sections by clicking a button.  The button graphics can be modified and are shared between all items (see SetButtons).  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 are enabled using SetShowButtons and SetShowButton0.  The location of an expand/collapse button can be determined using the GetExpandCollapseButtonRect function.

Expand/collapse buttons for individual items can be suppressed using the SetItemExpandCollapseButton function.

Tree Components