title: How to create a toggle/radio item in the menu/toolbar of an Eclipse e4 application?
body: <p>What is the canonical way of creating a menu item that implements a toggle or radio state in an eclipse e4 rcp application?</p>
  <p>It seems such a basic thing, but all the documentation I found relies on e3 API and creates dependencies to org.eclipse.ui, which is not allowed in e4.</p>