Tree(TreeGrid) Specific HowTos

How can I mark an item as a leaf or a branch of the tree?

In the RequestHasChildren event handler you are allowed to mark an item as a leaf or a branch. For this purpose, you should use the HasChildren property and set it to true or false. true marks an item as a branch, false - as a leaf.

dhtmlxTreeGridConnector connector = new dhtmlxTreeGridConnector(/*...*/);
connector.RequestHasChildren += new EventHandler<RequestChildrenEventArgs<dhtmlxTreeGridDataItem>>(
connector_RequestHasChildren
);
 
void connector_RequestHasChildren(object sender,RequestChildrenEventArgs<dhtmlxTreeGridDataItem> e)
{
    if (TodayIsMonday)
        e.HasChildren = false;//no children on Mondays
    else
        e.HasChildren = true;
}

For more details see the 'Tree/TreeGrid specific' chapter in the 'Dynamic loading' guide.