private const int NullKey = 0;
         private const int WM_HOTKEY = 786;
         protected internal short hotkeyID = 0;

         [DllImport("user32.dll")]
         public static extern bool RegisterHotKey(IntPtr hWnd, int id, int fsModifiers, int vlc);
         [DllImport("user32.dll")]
         public static extern bool UnregisterHotKey(IntPtr hWnd, int id);

//Form Load Event

RegisterHotKey(this.Handle, hotkeyID, NullKey,(int) Keys.PrintScreen);


//Form Closed event
UnregisterHotKey(this.Handle, hotkeyID);


//Check for key presses
 protected override void WndProc(ref System.Windows.Forms.Message m)
 {
    
     if (m.Msg == WM_HOTKEY) {

         CaptureScreen();
        
     }
    
     base.WndProc(ref m);
    
 }



//Other stuff when the app minimizes or goes into normal mode events

        private void FocusForm(object sender, EventArgs e)
        {
            this.WindowState = FormWindowState.Normal;
            this.ShowInTaskbar = true;
            notifyIcon1.Visible = false;
        }

        private void FocusForm1(object sender, EventArgs e)
        {
            if (this.WindowState == FormWindowState.Minimized)
            {
                this.ShowInTaskbar = false;
                notifyIcon1.Visible = true;
            }
        }