// mhook.h
#ifndef _mhook_
#define _mhook_

#include <windows.h>
#include <string>
#include <iostream>
#using <system.dll>

using namespace std;

#if defined DLL_EXPORT
#define DECLDIR __declspec(dllexport)
#else
#define DECLDIR __declspec(dllimport)
#endif

using namespace System;
extern "C"
{
	DECLDIR BOOL InstallHook();
	DECLDIR BOOL UninstallHook();

	LRESULT CALLBACK MouseProc(int nCode, WPARAM, LPARAM);
}

#endif

Meine dll.cpp sieht so aus:

// Dies ist die Haupt-DLL.

#include "stdafx.h"

#include "mhook.h"

//#define DLL_EXPORT

#pragma data_seg("shared")
// Globale Variablen 
HHOOK g_hMouseHook = NULL; // Handle unseres Hooks (als "shared" Deklariert) 
HINSTANCE g_hInst = NULL;     // Handle der DLL selbst 

#pragma data_seg()
#pragma comment(linker, "/SECTION:shared,RWS")

extern "C"{
	#pragma unmanaged
	BOOL APIENTRY DllMain (	HINSTANCE hInst     /* Library instance handle. */ , 
									DWORD reason        /* Reason this function is being called. */ , 
									LPVOID reserved     /* Not used. */ ){ 
		g_hInst = hInst; 

		return TRUE; 
	}

	DECLDIR BOOL InstallHook(){ 
			if(g_hMouseHook != NULL) 
				return TRUE; 
			g_hMouseHook = SetWindowsHookEx(WH_MOUSE, MouseProc, g_hInst, 0); 
			if(g_hMouseHook == NULL) {
				DWORD error = GetLastError();
				char* temp;
				temp = new char[100];
				sprintf(temp, "%d", error);
				MessageBoxA(NULL,LPCSTR(temp) ,NULL,MB_OK);
				delete []temp;
				return FALSE; 
			}
			return TRUE; 
		} 

	DECLDIR BOOL UninstallHook(){ 
		if(g_hMouseHook != NULL) 
		{ 
			BOOL ret = UnhookWindowsHookEx(g_hMouseHook);
			g_hMouseHook = NULL;
			if(ret==FALSE){
				DWORD error = GetLastError();
				char* temp;
				temp = new char[100];
				sprintf(temp, "%d", error);
				MessageBoxA(NULL,LPCSTR(temp) ,NULL,MB_OK);
				delete [] temp;
				return FALSE;
			}

		} 
		return TRUE; 
	}

	LRESULT CALLBACK MouseProc(int nCode, WPARAM wParam, LPARAM lParam)	{ 
		if (nCode < 0) 
		return CallNextHookEx(g_hMouseHook, nCode, wParam, lParam); 
		if(nCode == HC_ACTION) 
			{ 
			if ( (wParam == WM_RBUTTONDOWN) ) { 
				MOUSEHOOKSTRUCT *mhs = (MOUSEHOOKSTRUCT*)lParam; 

				HWND caller = FindWindowA("WindowsForms10.Window.8.app.0.378734a","meinprog");
				if(caller != NULL) 
					PostMessage(caller, WM_APP+123, 0, MAKELPARAM(mhs->pt.x, mhs->pt.y)); 
			} 
		} 
		return CallNextHookEx(g_hMouseHook, nCode, wParam, lParam); 
	}
}

GetLastError() liefert in der InstallHook dann übrigens auch 0.

Der Load-Code:

hInstLibrary = LoadLibraryA("E:\\Eigene Dateien\\Visual Studio 2008\\Projects\\mhook\\Debug\\mhook.dll");
			if(hInstLibrary){
				InstallHook = (MYFUNC) GetProcAddress(hInstLibrary, "InstallHook"); 
				if(InstallHook == NULL) { 
					MessageBoxA(NULL, "Error: Installhook not found", "Error",  MB_ICONHAND|MB_OK|MB_TOPMOST);					
				} 
				UninstallHook = (MYFUNC) GetProcAddress(hInstLibrary, "UninstallHook"); 
				if(UninstallHook == NULL) { 
					MessageBoxA(NULL, "Error: Uninstallhook not found", "Error", MB_ICONHAND|MB_OK|MB_TOPMOST); 
					return; 
				}			
			}

install und uninstall vom hook in der checkedChanged:

if(!hInstLibrary)
					this->CBShortcuts->Checked=false;
				if(this->CBShortcuts->Checked){
					if(hInstLibrary){
						BOOL ret = InstallHook();
						if(ret == FALSE) 
							MessageBoxA(NULL, "InstallHook failed!", "Error!", MB_OK|MB_TOPMOST); 

					}
					else this->CBShortcuts->Checked = false;
				}
				else{
					if(hInstLibrary){
						BOOL ret = UninstallHook();
						if(ret == FALSE) 
							MessageBoxA(NULL, "UninstallHook failed!", "Error!", MB_OK|MB_TOPMOST); 
					}
				}

Hat jemand eine Idee woran es liegt?

danke im voraus
veio

Das Betriebssystem garantiert nicht, daß eine DLL in jedem Prozess an die gleiche Adresse gemappt wird.

Probier mal das :

g_hMouseHook = SetWindowsHookEx(WH_MOUSE, MouseProc, g_hInst, GetCurrentThreadId ());

Dann bleibt der Hook lokal und (vorerst) gut ist.