OnClientDropDownOpening

The OnClientDropDownOpening client-side event that is fired before the dropdown of RadDropDownTree is opened.

The event handler receives two parameters:

1. The instance of the RadDropDownTree client-side object.

2. An Event argument parameter.

The event can be cancelled - simply set args.set_cancel to true - args.set_cancel(true); from the event handler and the RadDropDownTree dropdown will not be opened.

Scroll into view to a selected node

In OnClientDropDownOpening client-side event of RadDropDownTree we can scroll to the selected entry by using scrollIntoView() function of the node as in the code below:

function OnClientDropDownOpening(sender, args) {
    var tree = sender.get_embeddedTree(),
        node = tree.get_selectedNode();
    if (node) {
        node.scrollIntoView();
    }
}