C#

using System;
using System.Runtime.InteropServices;
using System.Windows.Forms;
using System.Web.Services;
using Microsoft.Win32;
using SHDocVw;

namespace KeyboardHooks_BHO
{
	
	/// <summary>
	/// Summary description for Class1.
	/// </summary>
	/// 
	[ComVisible(true)]
	[Guid("20C718C8-0D8C-42dc-B0CD-C7C53A23F116")]
	public class BHO	: IObjectWithSite
	{
		#region Member Variables
		protected SHDocVw.IWebBrowser2 m_pIWebBrowser2; // the browser class object
		protected SHDocVw.DWebBrowserEvents2_Event  m_pDWebBrowserEvents2; // browser events
//		private ComImports KeyHook= new ComImports();
		
		#endregion

		#region Hook Variables

		public struct KeyboardHookStruct
		{
			public long vkCode;
			public long scanCode;
			public int flags;
			public long time;
			public long dwExtraInfo;

		};
		private const int HC_ACTION = 0;
		private const int LLKHF_EXTENDED = 0x01;
		private const int LLKHF_ALTDOWN = 0x20;
		private const long VK_T = 0x54;
		private const long VK_P = 0x50;
		private const long VK_S	= 0x53;
		private const int WH_KEYBOARD_LL=13;

		protected IntPtr KeyboardHandle = IntPtr.Zero;
		private static int mHook;
		#endregion

		
		public BHO()
		{
	
			MessageBox.Show("inside BHO's constructor");
		}


		#region COM interfaces
		#region IObjectWithSite Members

		public void SetSite(object newSite)
		{
			MessageBox.Show("inside SetSite");
			object site=newSite;
			string explorer= null;
			
			if (m_pIWebBrowser2!=null)
				Release();

			if( site != null )
				Marshal.ReleaseComObject( site );

			site = newSite;
			
			if( site != null )
			{
				MessageBox.Show("inside if site!=null");
				IServiceProvider sp = site as IServiceProvider;
				m_pIWebBrowser2 = site as SHDocVw.IWebBrowser2;
				Guid guid = ExplorerGUIDs.IID_IWebBrowserApp;
				Guid riid = ExplorerGUIDs.IID_IUnknown;

				object wba;
				sp.QueryService(ref guid,ref riid,out wba );
		
				/*explorer = (WebBrowserClass)Marshal.CreateWrapperOfType(
					wba as SHDocVw.IWebBrowser2,
					typeof(WebBrowserClass));*/

				explorer=m_pIWebBrowser2.FullName.ToUpper();

				if(explorer.EndsWith("IEXPLORE.EXE"))
				{
					MessageBox.Show("inside the IEXPLORE.EXE");
//					KeyHook.Install();
					Install();
					MessageBox.Show("hooking");

				}
			}
			else
			{
				if ( explorer != null )
				{
					IServiceProvider sp = site as IServiceProvider;
					m_pIWebBrowser2 = site as SHDocVw.IWebBrowser2;
					Guid guid = ExplorerGUIDs.IID_IWebBrowserApp;
					Guid riid = ExplorerGUIDs.IID_IUnknown;

					object wba;
					sp.QueryService(ref guid,ref riid,out wba );

					explorer=m_pIWebBrowser2.FullName.ToUpper();
					//Marshal.ReleaseComObject( explorer );

					//explorer is about to close, freeing resources
					if(explorer.EndsWith("IEXPLORE.EXE"))
					{
						//KeyHook.UnInstall();
						UnInstall();
						MessageBox.Show("UnHookMe");
					}

					explorer = null;
				}
				MessageBox.Show("end of setsite");
				return;
			}

		}

		public int GetSite(ref Guid guid, out IntPtr ppvSite)
		{
			// TODO:  Add BHO.GetSite implementation
			MessageBox.Show("inside getsite");
			ppvSite = new IntPtr ();
			return 0;
		}

		#endregion

		protected void Release()
		{
			if (m_pDWebBrowserEvents2!=null)
			{
				Marshal.ReleaseComObject(m_pDWebBrowserEvents2);
				m_pDWebBrowserEvents2=null;
			}

			if (m_pIWebBrowser2 != null)
			{
				Marshal.ReleaseComObject(m_pIWebBrowser2);
				m_pIWebBrowser2 = null;
			}
		}
		
		#endregion

		#region Hook Functions

		private delegate int KeyboardHookProcDelegate(int nCode, int wParam, int lParam); 

		public void Install()
		{
			MessageBox.Show("inside Install");
			mHook=SetWindowsHookEx(WH_KEYBOARD_LL,new KeyboardHookProcDelegate(KeyboardHookProc),IntPtr.Zero,0);
			if(mHook!=0)
			{
				MessageBox.Show("unable to install");
			}
			else
				MessageBox.Show("Success in Installing!");
		}


		public static int KeyboardHookProc(int nCode, int wParam, int lParam) 
		{
			KeyboardHookStruct HookStruct;
			int ret = 0;
			MessageBox.Show("inside HookProc");

			HookStruct = (KeyboardHookStruct) Marshal.PtrToStructure(new IntPtr(lParam), typeof(KeyboardHookStruct));
			long vkCode= HookStruct.vkCode;
			int flag = HookStruct.flags;

			if(nCode==HC_ACTION)
			{
				MessageBox.Show("inside nCode==HC_ACTION");
				//System.Windows.Forms.Keys  KeyPressed = (Keys)wParam.ToInt32();

				// Insert + T  OR Alt + T
				if(vkCode == VK_T )
				{
					if(flag==LLKHF_EXTENDED)
					{
						MessageBox.Show("Play");
						ret=1;
					}
					else if((flag & LLKHF_ALTDOWN)!=0)
					{
						MessageBox.Show("Stop");
						ret=1;
					}
				}
				else if((vkCode == VK_P)&&((flag & LLKHF_EXTENDED)!=0))
				{ // Insert + P
					MessageBox.Show("pause");
					ret = 1 ;
				}
				else if((vkCode == VK_S) && ((flag & LLKHF_ALTDOWN)!=0))
				{ // Alt + S
					MessageBox.Show("Save");
					ret = 1 ;
				}
            	
				/*/	CopyMemory(HookStruct,lParam,sizeof(HookStruct);
					if(IsHooked(HookStruct))
						{
							MyKeyboardProc=1;
						}*/

				//	MyKeyboardProc=1;
			}
			if( ret == 0 )
			{
				ret = CallNextHookEx(mHook,nCode,wParam,lParam);
			}
			return ret;
		}
		

		public void UnInstall()
		{
			MessageBox.Show("inside UnInstall");
			if(mHook!=0)
			{
				MessageBox.Show("inside mHook!=0 ");
				UnhookWindowsHookEx(KeyboardHandle);
			}
		}


		#endregion

		#region Hook Win32Imports

		// Win32: SetWindowsHookEx()
		[DllImport("user32.dll")]
		private static extern int SetWindowsHookEx(int code, 
			KeyboardHookProcDelegate func,
			IntPtr hInstance,
			int threadID);

		// Win32: UnhookWindowsHookEx()
		[DllImport("user32.dll")]
		protected static extern int UnhookWindowsHookEx(IntPtr hhook); 


		// Win32: CallNextHookEx()
		[DllImport("user32.dll")]
		protected static extern int CallNextHookEx(int hhook, 
			int code, int wParam, int lParam);
		#endregion


	}
}


My questions are:
1.why is the hooks not working?
2.is there any issues related to the virtual key values and extended flags?
3.the hook procedure is not getting called. Is the definition correct?

hoping this is clear.
thanks and regards,
hema