null reference exception when calling Open()

Docking/MDI for WPF Forum

Posted 10 years ago by John Dunn
Version: 10.1.0521
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I'm getting a null reference exception when attempting to open a simple DocumentWindow. I assume it's something I'm missing. The XAML is

<UserControl x:Class="DocumentContainer"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:docking="http://schemas.actiprosoftware.com/winfx/xaml/docking">
  <docking:DockSite x:Name="_DockSite">
    <docking:TabbedMdiHost
      CanDocumentsDockBottom="False"
      CanDocumentsDockLeft="False"
      CanDocumentsDockRight="False"
      >
      <docking:TabbedMdiContainer x:Name="_TabHost">
      </docking:TabbedMdiContainer>
    </docking:TabbedMdiHost>
  </docking:DockSite>
</UserControl>
and I'm using the following code to create and open my document

      DocumentWindow doc = new DocumentWindow(_DockSite)
      {
        Title = "test",
        Content = new TextBlock() { Text = "this is a test" },
      };
      doc.Open();
The .Open call throws a null reference exception. The InnerException is null.

Comments (1)

Posted 10 years ago by John Dunn
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Fixed it - I was missing the Workspace from my XAML -

<UserControl x:Class="DocumentContainer"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:docking="http://schemas.actiprosoftware.com/winfx/xaml/docking">
  <docking:DockSite x:Name="_DockSite">
    <docking:Workspace>
      <docking:TabbedMdiHost>
        <docking:TabbedMdiContainer x:Name="_TabHost">
        </docking:TabbedMdiContainer>
      </docking:TabbedMdiHost>
    </docking:Workspace>
  </docking:DockSite>
</UserControl>
One odd behavior I'm still seeing is that if all my documents are currently 'rafted', I can't drag them back into the TabbedMdiContainer. If I then add a new page directly to the TabbedMdiContainer I can then drag the rafted windows back in. The 'Dock' command on the rafted window does work. Is this by design?
The latest build of this product (v2019.1 build 0683) was released 1 month ago, which was after the last post in this thread.

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