Hi Telerik Support Team,

I would like to request a feature enhancement for the Kendo UI for Angular TreeList component, specifically regarding the selection mechanisms.

Feature Request:

Please consider adding a (selectAllChange) event emitter to the <kendo-treelist-checkbox-column> component, similar to how selection events are handled or how other advanced components expose header checkbox interactions.

Use Case / Motivation:

Currently, when a user clicks the "Select-All" checkbox in the header, it is difficult to intercept this specific action efficiently to run custom business logic, perform secondary async operations, or manually update external states that depend strictly on the "all selected/unselected" toggle.

While we can listen to general selection changes on the TreeList, having a dedicated (selectAllChange) event that emits the current state (e.g., true, false, or even a custom event object) would provide much cleaner control over the application state, especially in complex data-binding scenarios.

Proposed Syntax:

<kendo-treelist-checkbox-column 
    [showSelectAll]="true" 
    (selectAllChange)="onSelectAllChange($event)">
</kendo-treelist-checkbox-column>