Because a call to the FreeLibrary function cannot be made for another process, there is then no way to free the DLL. This is because global hook procedures are called in the process context of every application in the desktop, causing an implicit call to the LoadLibrary function for all of those processes. You can release a global hook procedure by using UnhookWindowsHookEx, but this function does not free the DLL containing the hook procedure. Release a hook procedure as soon as your application no longer needs it. You can release a thread-specific hook procedure (remove its address from the hook chain) by calling the UnhookWindowsHookEx function, specifying the handle to the hook procedure to release. HkprcSysMsg = (HOOKPROC)GetProcAddress(hinstDLL, 'SysMessageProc') HinstDLL = LoadLibrary(TEXT('c:\myapp\sysmsg.dll')) This sequence is shown in the following example. SetWindowsHookEx passes the module handle, a pointer to the hook-procedure entry point, and 0 for the thread identifier, indicating that the hook procedure should be associated with all threads in the same desktop as the calling thread.

Finally, use SetWindowsHookEx to install the hook procedure address in the appropriate hook chain. After you have obtained the handle, you can call the GetProcAddress function to retrieve a pointer to the hook procedure.

To retrieve a handle to the DLL module, call the LoadLibrary function with the name of the DLL. The installing application must have the handle to the DLL module before it can install the hook procedure. You must place a global hook procedure in a DLL separate from the application installing the hook procedure. You can install a hook procedure by calling the SetWindowsHookEx function and specifying the type of hook calling the procedure, whether the procedure should be associated with all threads in the same desktop as the calling thread or with a particular thread, and a pointer to the procedure entry point.

Installing and Releasing Hook Procedures.

The following code examples demonstrate how to perform the following tasks associated with hooks:

For windows instal Fishing Hook