The aggregates field is currently available only for kendoTreeListFooterTemplate:

https://www.telerik.com/kendo-angular-ui/components/treelist/aggregates/#toc-aggregating-flat-data

But in some scenarios, the aggregates need to be displayed inside the headers as well. Please provide the aggregates field in the kendoGridCellTemplate.

So far the only approach where this can be achieved is to use manual aggregation and some custom code:

   <ng-template kendoTreeListCellTemplate let-dataItem>
                    {{dataItem.name}} - <strong> {{ data.aggregates.name.count }} employee(s)</strong>
</ng-template>

Provide a built-in functionality for the TreeList that would allow binding the component to data with the following structure:

const data = [
    { path: ['node1', 'node2'], property1: value, property2: value },
    { path: ['node1', 'node2', 'node3'], property1: value, property2: value },
];

The structure provides particular paths for the leaf nodes (last children) that determine the hierarchy within the component and additional fields that correspond to the columns' definition of the component. 

The drag selection is enabled immediately after dragging the cursor a little (1-2px). This causes issues when a row is expanded/collapsed first then clicking the checkbox as sometimes, the cursor is dragged in the checkbox. Then drag selection resets the previously selected rows. Here is a screencast of the issue:

https://screenrec.com/share/y6pPGWjUZH

1. Expand a row
2. Click and drag the cursor in the checkbox (1-2px)

https://stackblitz.com/edit/angular-qnaphv-2nszye

The drag selection should not be enabled.

The Grid has a logic for enabling the drag selection after N-pixels of dragging. Could be reused in TreeList as well.