Feature request: ability to multiple select TreeView items on click

As far as I’m aware it’s currently only possible to multi-select items in a TreeView by holding down a keyboard modifier (cmd or shift on macOS).

It would be very useful if it could be configured so that multiple items can be selected and de-selected, e.g. by single-click. Currently AFAICT, this is only possible by modifying TreeView::ContentComponent directly.