psible-content"><div class="qm-api-item-content"><div class="qm-api-description"><div class="qm-html-paragraph">Create one of these for each tree layout in your page. This object provides a way to fill out tree layouts from an array of objects, and also makes it possible to listen out for tree expansion and contraction events. It also makes it possible to expand &#x2F; collapse parts of the tree using the api. </div></div><div class="qm-api-group qm-api-constructor-group"><div class="qm-api-group-header qm-