Управление программами

static class Program
    {
        [DllImport("user32.dll", EntryPoint = "FindWindow")]
        private static extern IntPtr FindWindow(string _ClassName, string _WindowName);
 
        [DllImport("user32.dll", EntryPoint = "FindWindowEx")]
        private static extern IntPtr FindWindowEx(IntPtr hwndPrnt, IntPtr hwndChildAfter, string _ClassName, string _WindowName);
 
        [DllImport("user32.dll", CharSet = CharSet.Auto)]
        public static extern int SendMessage(IntPtr hwnd, int wMsg, IntPtr wParam, IntPtr lParam);
        const int WM_LBUTTONDOWN = 513;
        const int WM_LBUTTONUP = 514;
        const int WM_RBUTTONDOWN = 516;
        const int WM_RBUTTONUP = 517;
        const int WM_SETTEXT = 0x000C;
 
        [DllImport("user32.dll", EntryPoint = "SendMessage", CharSet = CharSet.Auto)]
        private static extern IntPtr SendMessageText(IntPtr hWnd, int wMsg, int wParam, string lParam);
 
        [STAThread]
        static void Main()
        {
            Application.EnableVisualStyles();
            Application.SetCompatibleTextRenderingDefault(false);
            Application.Run();
        }
        
        public static void FindEditWindows(string message)
        {
            IntPtr calcWindow = FindWindow("SciCalc", "Calculator");
            if (calcWindow == IntPtr.Zero)
            {
                MessageBox.Show("Not found Calculator window");
                return;
            }
            IntPtr editWindow = FindWindowEx(calcWindow, IntPtr.Zero, "Edit", null);
            if (editWindow == IntPtr.Zero)
            {
                MessageBox.Show("Not found Edit");
                return;
            }
            SendMessageText(editWindow, WM_SETTEXT, 0, message);
        }