[Feature Request] Add active class at top level of active tree node

[severdia]

I'd like to do some CSS customizations to the tree and need an "active" class on the "treeview" <div> here:

You have "is-folder-active" when the item is selected, but it would be even better to have a similar class such as:

<div class="treeview is-active" draggable="true">

More customization possibilities are possible. Thanks!