Topmost属性控制窗口置顶，WindowState属性控制窗体最大化，最小化，还原等状态。

private void SetTopMost_Checked(object sender, RoutedEventArgs e)
{
    Topmost = SetTopMost.IsChecked is true;
}

private void btnMinsize_Click(object sender, RoutedEventArgs e)
{
    WindowState = WindowState.Minimized;
}

private void btnNormal_Click(object sender, RoutedEventArgs e)
{
    WindowState = WindowState.Normal;
}

private void btnMnsize_Click(object sender, RoutedEventArgs e)
{
    WindowState = WindowState.Maximized;
}