Manipulating Windows using messages and simple CBT hooking

// DemoDll.cpp : Defines the entry point for the DLL application.
//

#include "stdafx.h"
#include "DemoDll.h"
#include "shellapi.h"
#include "tchar.h"

HINSTANCE g_hModule =  NULL;

#pragma data_seg(".HookDll")
HWND g_hWndEffects = NULL;
HHOOK g_hook = NULL;
#pragma data_seg()
#pragma comment(linker, "/section:.HookDll,rws")



BOOL APIENTRY DllMain( HANDLE hModule, 
					  DWORD  ul_reason_for_call, 
					  LPVOID lpReserved
					  )
{
	g_hModule = (HINSTANCE)hModule;
	switch (ul_reason_for_call)
	{
	case DLL_PROCESS_ATTACH:
	case DLL_THREAD_ATTACH:
	case DLL_THREAD_DETACH:
	case DLL_PROCESS_DETACH:
		break;
	}
	return TRUE;
}


DEMODLL_API BOOL ToggleMenuUnderline(void)
{
	HWND hWndAppearance = NULL;
	BOOL ret = TRUE;

	g_hook = SetWindowsHookEx(WH_CBT, CBTProc, g_hModule, 0); 

	ret = BringUpDisplayAppearance();
	Sleep(500);//Wait for the window to come up
	if(ret)
	{
		hWndAppearance = FindWindow(NULL,
			_T("Display Properties"));
		ret = hWndAppearance != NULL;		

		if(ret)
		{
			HWND hWndEffectsButton = GetEffectsButton(hWndAppearance);
			ret = hWndEffectsButton != NULL;

			if(ret)
			{
				PostMessage(hWndEffectsButton,BM_CLICK,0,0);	

				//Wait for the Effects window to come up	
				while(!IsWindow(g_hWndEffects))
					Sleep(100);			

				HWND hWndCheck = GetMenuUnderlineCheck(g_hWndEffects);

				ret = hWndCheck != NULL;

				if(ret)
				{						
					PostMessage(hWndCheck,BM_CLICK,0,0);										
					PostMessage(g_hWndEffects,WM_COMMAND,IDOK,NULL);
					PostMessage(hWndAppearance,WM_COMMAND,IDOK,NULL);

					//Wait for the window to be dismissed
					while(IsWindow(hWndAppearance))
						Sleep(100);				
				}
			}
		}
	}

	//Final checks in case of error conditions
	if(IsWindow(g_hWndEffects))
		PostMessage(g_hWndEffects,WM_CLOSE,0,0);
	if(IsWindow(hWndAppearance))
		PostMessage(hWndAppearance,WM_CLOSE,0,0);

	return ret;
}

BOOL BringUpDisplayAppearance()
{
	return reinterpret_cast<int>(ShellExecute(GetDesktopWindow(),
		"open","control.exe","desk.cpl Display,@Appearance",
		"",SW_SHOW )) > 32 ? TRUE : FALSE;	
}

HWND GetEffectsButton(HWND hWndParent)
{
	HWND hWnd = NULL;

	EnumChildWindows(hWndParent, EnumAppearanceChildProc, (LPARAM)&hWnd);
	return hWnd;
}

BOOL CALLBACK EnumAppearanceChildProc(HWND hwnd, LPARAM lParam)
{
	TCHAR buff[512];
	GetWindowText(hwnd,buff,512);	
	if(_tcscmp(buff,_T("&Effects...")) == 0)
	{		
		*reinterpret_cast<HWND*>(lParam) = hwnd;
		return FALSE;
	}
	return TRUE;
}

HWND GetMenuUnderlineCheck(HWND hWndParent)
{
	HWND hWnd = NULL;	
	EnumChildWindows(hWndParent, EnumEffectsChildProc, (LPARAM)&hWnd);
	return hWnd;
}

BOOL CALLBACK EnumEffectsChildProc(HWND hwnd, LPARAM lParam)
{
	TCHAR buff[512];
	GetWindowText(hwnd,buff,512);	
	if(_tcsstr(buff,_T("&Hide underlined")))
	{		
		*reinterpret_cast<HWND*>(lParam) = hwnd;
		return FALSE;
	}
	return TRUE;
}

LRESULT CALLBACK CBTProc(int nCode, WPARAM wParam, LPARAM lParam)
{
	if(nCode == HCBT_ACTIVATE)
	{
		HWND hWnd = (HWND) wParam;
		TCHAR buff[512];
		GetWindowText(hWnd,buff,512);
		if(_tcscmp(buff,_T("Effects")) == 0)
		{	
			ShowWindow(hWnd,SW_HIDE);
			g_hWndEffects = hWnd;		
			UnhookWindowsHookEx(g_hook);						
		}
		if(_tcscmp(buff,_T("Display Properties")) == 0)
		{				
			ShowWindow(hWnd,SW_HIDE);											
		}
	}

	return 0;
}