Hello,

In my MainWindow I call OnInitialized a XamDialogWindow and add it to the UICollection of a grid:

XamDialogWindow _logon = new XamDialogWindow ();

this.DialogAddContainer.Children.Add(_logon);

My MainWindow has only, something like this:

<Window ...

 <Grid Name="DialogAddContainer">

<Grid >

// content

</Grid>

</Grid>

And my XamDialogwindow is in a UserControl:

<UserControl.....

<my:XamDialogWindow 

IsModal="True" 

So when my goal is to display the dialog window at startup Modal over the rest of my application 

and it should be have an alignment  the center of the window.

So I get this when setting my UserControl Horizontal and VerticalAlignment to center, then the 

XamDialogWindow  is displayed in the center of my Window but it is no longer Modal. 

How can I get the XamDialogWindow in a Usercontrol to the center of an window and keep it Modal of

my hole window?

regards