title: Invalid signal parameter type: MouseEvent
body: <p>If I try and use a <code>MouseEvent</code> as an arg in a QML defined signal, I get the following error on load:</p>
  
  <blockquote>
    <p>Invalid signal parameter type: MouseEvent</p>
  </blockquote>
  
  <p>There is conflicting information in the Qt docs regarding this, in the <a href="http://doc.qt.io/qt-5/qtqml-syntax-objectattributes.html#signal-attributes" rel="nofollow noreferrer">QML signal syntax documentation</a> it states that:</p>
  
  <blockquote>
    <p>The allowed parameter types are the same as those listed under Defining Property Attributes [...] any QML object type can be used as a property type.</p>
  </blockquote>
  
  <p>Whilst in the <a href="http://doc.qt.io/qt-5/qtqml-cppintegration-interactqmlfromcpp.html#connecting-to-qml-signals" rel="nofollow noreferrer">QML/C++ interaction documentation</a> it states that:</p>
  
  <blockquote>
    <p>When a QML object type is used as a signal parameter, the parameter should use var as the type</p>
  </blockquote>
  
  <p>Setting the argument to use <code>var</code> does work, but this seems unnecessary according to the QML documentation.  There was a bug regarding this <a href="https://bugreports.qt.io/browse/QTBUG-14550" rel="nofollow noreferrer">in the distant past</a> but it was apparently resolved in v5.0.0.  So I am doing something wrong, or is this a regression?</p>
  
  <h2>Edit</h2>
  
  <p>A simple demonstration:</p>
  
  <pre><code>import QtQuick 2.3
  
  Item {
      signal sig( MouseEvent mouse )
  }
  </code></pre>