BringToFront, SendToBack, but no BringForward or SendBackward?

Hi and thanks. The solution works fine.
A few tips for others who have the same problem. GetNextWindow didn't work for me - DllImport said there's no such function as GetNextWindow, so it's probably just a buffer name for GetWindow used in user32.lib import library. As the documentation said though - GetWindow works just about the same and can be easily imported in C#.

[DllImport("user32.dll", EntryPoint = "SetWindowPos")]
public static extern bool SetWindowPos(
      IntPtr hWnd, // window handle
      IntPtr hWndInsertAfter, // placement-order handle
      int X, // horizontal position
      int Y, // vertical position
      int cx, // width
      int cy, // height
      uint uFlags); // window positioning flags
public const uint SWP_NOSIZE = 0x1;
public const uint SWP_NOMOVE = 0x2;
public const uint SWP_SHOWWINDOW = 0x40;
public const uint SWP_NOACTIVATE = 0x10;

[DllImport("user32.dll", EntryPoint = "GetWindow")]
public static extern IntPtr GetWindow(
      IntPtr hWnd,
      uint wCmd);
public const uint GW_HWNDFIRST = 0;
public const uint GW_HWNDLAST = 1;
public const uint GW_HWNDNEXT = 2;
public const uint GW_HWNDPREV = 3;

public static void ControlBringToFront(Control control)
{
      bool s = SetWindowPos(
            control.Handle,
            GetWindow(GetWindow(control.Handle, GW_HWNDFIRST), GW_HWNDPREV),
            0, 0, 0, 0,
            SWP_NOSIZE | SWP_NOMOVE | SWP_NOACTIVATE);
}

public static void ControlSendToBack(Control control)
{
      bool s = SetWindowPos(
            control.Handle,
            GetWindow(control.Handle, GW_HWNDLAST),
            0, 0, 0, 0,
            SWP_NOSIZE | SWP_NOMOVE | SWP_NOACTIVATE);
}

public static void ControlBringForward(Control control)
{
            if (GetWindow(control.Handle, GW_HWNDFIRST) == control.Handle)
                  return;
            SetWindowPos(
                  control.Handle,
                  GetWindow(GetWindow(control.Handle, GW_HWNDPREV), GW_HWNDPREV),
                  0, 0, 0, 0,
                  SWP_NOSIZE | SWP_NOMOVE | SWP_NOACTIVATE);
}

public static void ControlSendBackward(Control control)
{
            if (GetWindow(control.Handle, GW_HWNDLAST) == control.Handle)
                  return;
            SetWindowPos(
                  control.Handle,
                  GetWindow(control.Handle, GW_HWNDNEXT),
                  0, 0, 0, 0,
                  SWP_NOSIZE | SWP_NOMOVE | SWP_NOACTIVATE);
}

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What is interesting, .NET's Control class' Controls property returns the collection of controls ordered in their Z-Order, so after you design the whole collection you can store it in some resource file in the order from Control.Controls and when you read the form back - the controls will be in the same Z-Order you designed them to be in.