I have an answer for you that I found here (I don't speak Chinese so don't ask me what it says :). You have to set a hook. He provides a wrapper class. I repeat some code here without the Chinese characters. RegisterHotKey.cs ...
using System;
using System.Runtime.InteropServices;
using System.Windows.Forms;
namespace TestKeydown
{
public class RegisterHotKeyClass
{
private IntPtr m_WindowHandle = IntPtr.Zero;
private MODKEY m_ModKey = MODKEY.MOD_CONTROL;
private Keys m_Keys = Keys.A;
private int m_WParam = 10000;
private bool Star = false;
private HotKeyWndProc m_HotKeyWnd = new HotKeyWndProc();
public IntPtr WindowHandle
{
get { return m_WindowHandle; }
set { if (Star)return; m_WindowHandle = value; }
}
public MODKEY ModKey
{
get { return m_ModKey; }
set { if (Star)return; m_ModKey = value; }
}
public Keys Keys
{
get { return m_Keys; }
set { if (Star)return; m_Keys = value; }
}
public int WParam
{
get { return m_WParam; }
set { if (Star)return; m_WParam = value; }
}
public void StarHotKey()
{
if (m_WindowHandle != IntPtr.Zero)
{
if (!RegisterHotKey(m_WindowHandle, m_WParam, m_ModKey, m_Keys))
{
throw new Exception("");
}
try
{
m_HotKeyWnd.m_HotKeyPass = new HotKeyPass(KeyPass);
m_HotKeyWnd.m_WParam = m_WParam;
m_HotKeyWnd.AssignHandle(m_WindowHandle);
Star = true;
}
catch
{
StopHotKey();
}
}
}
private void KeyPass()
{
if (HotKey != null) HotKey();
}
public void StopHotKey()
{
if (Star)
{
if (!UnregisterHotKey(m_WindowHandle, m_WParam))
{
throw new Exception("");
}
Star = false;
m_HotKeyWnd.ReleaseHandle();
}
}
public delegate void HotKeyPass();
public event HotKeyPass HotKey;
private class HotKeyWndProc : NativeWindow
{
public int m_WParam = 10000;
public HotKeyPass m_HotKeyPass;
protected override void WndProc(ref Message m)
{
if (m.Msg == 0x0312 && m.WParam.ToInt32() == m_WParam)
{
if (m_HotKeyPass != null) m_HotKeyPass.Invoke();
}
base.WndProc(ref m);
}
}
public enum MODKEY
{
MOD_ALT = 0x0001,
MOD_CONTROL = 0x0002,
MOD_SHIFT = 0x0004,
MOD_WIN = 0x0008,
}
[DllImport("user32.dll")]
public static extern bool RegisterHotKey(IntPtr wnd, int id, MODKEY mode, Keys vk);
[DllImport("user32.dll")]
public static extern bool UnregisterHotKey(IntPtr wnd, int id);
}
}
Calling code in a Form ...
private RegisterHotKeyClass _RegisKey = new RegisterHotKeyClass();
void _Regis_HotKey()
{
MessageBox.Show("ok");
}
private void Form1_Load(object sender, EventArgs e)
{
_RegisKey.Keys = Keys.PrintScreen;
_RegisKey.ModKey = 0;
_RegisKey.WindowHandle = this.Handle;
_RegisKey.HotKey += new RegisterHotKeyClass.HotKeyPass(_Regis_HotKey);
_RegisKey.StarHotKey();
}