here is how you hide windows 7 start menu and show full windows in C# .net winform


        public System.Drawing.Color colorActiveColor = System.Drawing.Color.Black;
        private const int SW_HIDE = 0;
        private const int SW_SHOW = 1;

        [DllImport("user32.dll")]
        private static extern int FindWindow(string className, string windowText);
        [DllImport("user32.dll")]
        private static extern int ShowWindow(int hwnd, int command);
        [DllImport("user32.dll")]
        private static extern int EnableWindow(int hwnd, bool command);
        [DllImport("user32.dll")]
        private static extern int FindWindowEx(int hwndParent, int hwndChildAfter, string className, string windowText);
        [DllImport("user32.dll")]
        private static extern int GetDesktopWindow();
        
        int hwndParent = 0;
        int hwnd = 0;
        public void FullScreen()
        {

            HideStartMenu();
            menuStrip1.Visible = false;
            statusStrip1.Visible= false;
            frmMain.ActiveForm.TopMost = true;
            frmMain.ActiveForm.FormBorderStyle = FormBorderStyle.None;
            frmMain.ActiveForm.WindowState = FormWindowState.Maximized;
            panelMain.BackColor = System.Drawing.Color.Black;
            panelMain.Dock = DockStyle.Fill;
            
        }


        public void Normal()
        {

            menuStrip1.Visible = true;
            statusStrip1.Visible = true;
            frmMain.ActiveForm.WindowState = FormWindowState.Normal;
            frmMain.ActiveForm.FormBorderStyle = FormBorderStyle.Fixed3D;
            frmMain.ActiveForm.TopMost = false;
            panelMain.BackColor = colorActiveColor;
            panelMain.Dock = DockStyle.Fill;
            ShowStartMenu();
        }

        public void HideStartMenu()
        {
            hwndParent = FindWindow("Shell_TrayWnd", "");
            hwnd = FindWindowEx(GetDesktopWindow(), 0, "BUTTON", "Start");
            ShowWindow(hwndParent, SW_HIDE);
            ShowWindow(hwnd, SW_HIDE);

        }

        public void ShowStartMenu()
        {
            hwndParent = FindWindow("Shell_TrayWnd", "");
            hwnd = FindWindowEx(GetDesktopWindow(), 0, "BUTTON", "Start");
            ShowWindow(hwndParent, SW_SHOW);
            ShowWindow(hwnd, SW_SHOW);
        }