C# SetWindowText By Alix

public static extern bool SetWindowText(IntPtr hwnd, String lpString);

[DllImport("user32.dll", EntryPoint = "FindWindow", CharSet = CharSet.Ansi)]

public static extern IntPtr FindWindow(string className, string windowName);

   private void button4_Click_2(object sender, EventArgs e)
        {
            SetWindowText(FindWindow(null, "Growtopia"), YOUR TEXT!);
        }