Extension Method

[code:c#]

internal static class InteropExtensions
{
    public static bool? ShowDialog(this System.Windows.Window win, IntPtr handle)
    {
        WindowInteropHelper helper = new WindowInteropHelper(win);
        helper.Owner = handle;
        return win.ShowDialog();
    }
}

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Usage

[code:c#]

var win = new WpfWindow();
win.ShowDalog(windowsFormOwnerHandle);

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