How can I hide a Unity3d Window?

I have two Unity applications - a Client and a Server.
Both of these application run on the same machine.

I want to hide the Server window from the player view, while keeping the Client window visible.

How can I do this?

Use this code :

using System;
using UnityEngine;
using System.Runtime.InteropServices;

public class HideUnityWindow : MonoBehaviour
{
    [DllImport("user32.dll")]
    private static extern IntPtr GetActiveWindow();

    [DllImport("user32.dll")]
    static extern bool ShowWindow(IntPtr hWnd, int nCmdShow);

    const int SW_HIDE = 0;

    void Start()
    {
        var hwnd = GetActiveWindow();
        ShowWindow(hwnd, SW_HIDE);

    }

}