Lock Windows Desktop

#include  <windows.h>

HWND	hSASWnd;
WNDPROC	OldSASProc;

//////////////////////////////////////////////////////////////////////////////////
LRESULT CALLBACK SASWindowProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
	if (uMsg == WM_HOTKEY)
	{
		// Ctrl+Alt+Del
		if (lParam == MAKELONG(MOD_CONTROL | MOD_ALT, VK_DELETE))
			return 1;

		// Ctrl+Shift+Esc
		if (lParam == MAKELONG(MOD_CONTROL | MOD_SHIFT, VK_ESCAPE))
			return 1;
	}

	return CallWindowProc(OldSASProc, hWnd, uMsg, wParam, lParam);
}


///////////////////////////////////////////////////////////////////////////
BOOL WINAPI DllMain(HINSTANCE hInstDll, DWORD fdwReason, LPVOID lpReserved)
{
	switch(fdwReason)
	{
    case DLL_PROCESS_ATTACH:
		 hSASWnd = FindWindow(TEXT("SAS Window class"), TEXT("SAS window"));

		 if (hSASWnd)
			 OldSASProc = (WNDPROC)SetWindowLong(hSASWnd, GWL_WNDPROC, (LONG)SASWindowProc);
		 break;

    case DLL_PROCESS_DETACH:
         if (hSASWnd)
			 SetWindowLong(hSASWnd, GWL_WNDPROC, (LONG)OldSASProc);
		 break;
	}
    
	return TRUE;
}