Function start_pending_control_invocations 

pub fn start_pending_control_invocations(
    root: &mut dyn Widget,
    doc: &mut Edits<'_>,
    path: &ExId,
) -> usize

Run the queued control intents of a tree whose host keeps no resource tree of its own, such as the shell’s own UI: an intent is delivered to the control that published the action it names — a press (Button::on_effect, Button::on_view) and a control’s own verb (the value a field reports, the choice a picker made) alike — as a resource host delivers an admitted invocation. Answers how many ran.

Every other intent is the resource dispatcher’s and is dropped here.