/// <summary>
/// adds a Window to the Screen
/// </summary>
/// <param name="w">Window to add</param>
public void add(Window w)
{
if (wls.Count > 0)
wls.Last().HasFocus = false;
wls.Add(w);
w.HasFocus = true;
}
/// <summary>
/// removes a window from the Screen
/// </summary>
/// <param name="w"></param>
public void rem(Window w)
{
wls.Remove(w);
if (wls.Count > 0)
wls.Last().HasFocus = true;
}