WPF: dynamically adding a windowsformshost control to TabControl

Question

Hi All,

I am trying to add a control to a tabcontrol in the code. I have the following:

txUserControl htmlControl = new txUserControl(Utils.FileMode.Open, Utils.TxMode.Edit, 0);
System.Windows.Forms.Integration.WindowsFormsHost host = new
System.Windows.Forms.Integration.WindowsFormsHost();
host.Child = htmlControl;
DockPanel panel = new DockPanel();
panel.LastChildFill = true;
panel.Children.Add(host);
TabItem tb = new TabItem();
tb.Content = panel;
tb.Header = OpenDocument.Document;
tbControlStories.Items.Add(tb);
tb.Focus();

I have added a button as well to the panel, and the button is displayed, but not my control.

If I removed the tabcontrol and I put a dock panel instead, the control is displayed.

 <Grid>
 <Grid.RowDefinitions>
    <RowDefinition Height="30" MinHeight="0" MaxHeight="600"/>
    <RowDefinition Height="10"/>
    <RowDefinition/>
 </Grid.RowDefinitions>
 <StackPanel x:Name="StackPanelFields" Grid.Row="0">

 </StackPanel>
 <GridSplitter Grid.Row="1" ResizeDirection="Rows" HorizontalAlignment="Stretch" Height="3" Background="AliceBlue">
 </GridSplitter>
 <!--  <TabControl x:Name="tbControlStories" Grid.Row="2">
 </TabControl> -->
  <DockPanel x:Name="StackPanelStory" Grid.Row="2" LastChildFill="True">
  </DockPanel>

Then in the code behind:

StackPanelStory.Children.Add(host);

and it works, my control is diplayed as expected.

Could someone tell me what I am doing wrong?

Thanks