Wrong parent state when children are collapsed and `CheckDirective` is used

[Raisolution]

Could be reproduced in the following example

Steps to reproduce:

1. Use Mode Multiple
2. Expand the Furniture node
3. Check the Furniture node
4. Collapse the Furniture node
5. Unchecked the Furniture node - instead of clearing the checkbox, it's now ended up in intermediate state
6. Expand the Furniture node - all child are checked, but Furniture node is still in intermediate state
7. Check the Furniture node will change to correct behavior

Expected behavior: Parent state is correctly changed to unchecked after step 5.

Reported in ticket 1418042

Related to #2265 #2132

[tomasmejia]

I am dealing with the same bug. It should also uncheck all childs if the parent is collapsed and you uncheck it. Not sure how to fix it.

[cdtapay]

It's almost the end of the year. Any update on this? Thanks.

[midexsoftware]

It's almost end of 2021 and issue still have not been resolved. Please expedite this.

[yanmariomenev]

Recently mentioned in - 1566016, 1570900 and 1546612

[mbechev]

Currently, the workaround is to set the loadOnDemand property to false (by default it is true):

https://www.telerik.com/kendo-angular-ui/components/treeview/checkboxes/#toc-preloaded-nodes

Here is an example:

https://stackblitz.com/edit/angular-mkji7f

For the cases when the children need to be loaded on demand, there isn't an available solution yet.

[svetq]

When using [loadOnDemand]="true" the TreeView doesn't know of its collapsed nodes. This is why, unchecking a parent will not uncheck its collapsed children.

To achieve the required behavior, we added a new property uncheckCollapsedChildren. Set [uncheckCollapsedChildren]="true" to achieve the requirement.

The new property is available since @progress/kendo-angular-treeview v15.1.0.