Position of Primary Screen in Virtual Screen

Question

I can center a wpf window in somewhere in the primary screen or in the virtual screen. However, I want to stretch the window over the whole virtual screen and place e.g. a grid in the window in a way that it fills the primary screen. The following snipped shows how I stretch the window, add a grid and stretch the grid to fit the primary screen size, but how do I determine the position (i.e. margin) for the grid?

<Window x:Class="BC.Citrium.Screensaver.Saver.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" 
        Height="{x:Static SystemParameters.VirtualScreenHeight}" 
        Width="{x:Static SystemParameters.VirtualScreenWidth}"
        Top="{x:Static SystemParameters.VirtualScreenTop}"
        Left="{x:Static SystemParameters.VirtualScreenLeft}"
        ResizeMode="NoResize" WindowStyle="None">
    <Grid Name="mainGrid"
          Height="{x:Static SystemParameters.MaximizedPrimaryScreenHeight}" 
          Width="{x:Static SystemParameters.MaximizedPrimaryScreenWidth}"
          Margin="???"
          Background="Bisque">
    </Grid>
</Window>

I could draw two windows, one to fit the virtual screen and one above that to fit the primary screen, but that's not the nice way.

Answer 1

The upper left corner of the primary screen is always at screen position (0, 0). Which makes the margin you want to use (-VirtualScreenLeft, -VirtualScreenTop). With adjustment for the window border width and the window caption height.