title: .NET MAUI Community Toolkit Popup PopupHandler is incompatible
body: <p>I started working with .NET MAUI. I ran into a problem just by starting my development.
  I want to show a popup and I'm using the Community Toolkit.</p>
  <p>All I did is:</p>
  <p>I created a new .NET MAUI Application Project, installed the Community Toolkit NuGet Package (of course also the .UseMauiCommunityToolkit in the start up class) and added a XAML File for the Popup:</p>
  <pre><code>&lt;?xml version=&quot;1.0&quot; encoding=&quot;utf-8&quot; ?&gt;
  &lt;toolkit:Popup xmlns=&quot;http://schemas.microsoft.com/dotnet/2021/maui&quot;
                 xmlns:x=&quot;http://schemas.microsoft.com/winfx/2009/xaml&quot;
                 xmlns:toolkit=&quot;http://schemas.microsoft.com/dotnet/2022/maui/toolkit&quot;
                 x:Class=&quot;TestApp.ProfilePopup&quot;&gt;
  
      &lt;VerticalStackLayout&gt;
          &lt;Label Text=&quot;This is a very important message!&quot; /&gt;
      &lt;/VerticalStackLayout&gt;
  
  &lt;/toolkit:Popup&gt;
  </code></pre>
  <p>I've no partial class for this popup</p>
  <p>I just modified the button on MainPage to display the popup:</p>
  <pre><code>    private void OnCounterClicked(object sender, EventArgs e)
      {
  
          var popup = new ProfilePopup();
  
          this.ShowPopup(popup);
  
      }
  </code></pre>
  <p>If I run this application and click on the button to display the popup I'll get the error message:</p>
  <p><code>CommunityToolkit.Maui.Core.Handlers.PopupHandler found for TestApp.ProfilePopup is incompatible</code></p>
  <p>If I create the popup in C#, it works:</p>
  <pre><code>    private void OnCounterClicked(object sender, EventArgs e)
      {
          var popup = new Popup
          {
              Content = new VerticalStackLayout
              {
                  Children =
          {
              new Label
              {
                  Text = &quot;This is a very important message!&quot;
              }
          }
              }
          };
  
          this.ShowPopup(popup);
  
      }
  </code></pre>
  <p>Any idea what I'm doing wrong?</p>
  <p>Thank you!</p>
  <p>Markus</p>