Treeview event on clicking on item arrow

Hi, I am working on a project that uses treeview (5.1), and I understood that I can put an event on selecting or clicking on THE TEXT of the item. What if I need to act on clicking on the open/close ARROW of the item? This expand/collapse the item, but I wish a programmatic feedback of that clicking.

Hello. Unfortunately the treeView component has no expand/collapse event.
I can only suggest you to use the dhtmlxTree component instead of the dhtmlxTreeview:
It has the corresponded events: