title: func<string,string,bool> is not a valid windows runtime parameter type (win 8.1)
body: <p><a href="https://github.com/igorkulman/AutoCompleteBox/blob/master/AutoCompleteBox/AutoCompleteBox.cs" rel="nofollow">https://github.com/igorkulman/AutoCompleteBox/blob/master/AutoCompleteBox/AutoCompleteBox.cs</a></p>
  
  <p>I download this control, But I cannot build it,</p>
  
  <pre><code>public Func&lt;string, string, bool&gt; SearchFunction
  {
     get { return (Func&lt;string, string, bool&gt;)GetValue(SearchFunctionProperty); }
     set { SetValue(SearchFunctionProperty, value); }
  }
  </code></pre>
  
  <p>When I try using SearchFunction as public,I am getting this error. When I change it as internal it is working but this time I can't access SearchFunction from my project.</p>
  
  <pre><code>Method 'CodeAutoComplete.AutoCompleteBox.SearchFunction.get()' has a parameter of type
   'System.Func&lt;System.String, System.String, System.Boolean&gt;' in its signature. Although 
  this generic type is not a valid Windows Runtime type, the type or its generic parameters 
  implement interfaces that are valid Windows Runtime types. Consider changing the type 
  'System.Func&lt;T1, T2, TResult&gt;' in the method signature. It is not a valid Windows Runtime 
  parameter type. C:\\..CodeAutoComplete\AutoCompleteBox.cs CodeAutoComplete (Windows 8.1)
  </code></pre>
  
  <p>What should I do?</p>