title: Prevent a QMenu from closing when one of its QAction is triggered
body: <p>I'm using a QMenu as context menu. This menu is filled with QActions. One of these QActions is checkable, and I'd like to be able to check/uncheck it without closing the context menu (and having to re-open it again to choose the option that I want).</p>
  
  <p>I've tried disconnecting the signals emitted by the checkable QAction with no luck.</p>
  
  <p>Any ideas? Thanks.</p>