Prevents the game from freezing when interacting with the title bar.

unfreeze_messages.cpp

// reversed from https://gist.github.com/shavitush/0d25bc384b52412f035e959fc71d6ce4

auto __stdcall hooks::CreateWindowExA(DWORD dwExStyle, LPCSTR lpClassName, LPCSTR lpWindowName, DWORD dwStyle,
   int X, int Y, int nWidth, int nHeight, HWND hWndParent, HMENU hMenu, HINSTANCE hInstance, LPVOID lpParam) -> HWND
{
	auto hWnd = trampolines::CreateWindowExA(dwExStyle, lpClassName, lpWindowName, dwStyle, X, Y, nWidth, nHeight, hWndParent, hMenu, hInstance, lpParam);

	if(std::strcmp(lpClassName, "MapleStoryClass") == 0)
	{
		wndproc::original = reinterpret_cast<WNDPROC>(::SetWindowLongA(hWnd, GWLP_WNDPROC, reinterpret_cast<long long>(wndproc::custom_wndproc)));
	}

	return hWnd;
}

auto wndproc::custom_wndproc(HWND hWnd, unsigned int msg, unsigned int wParam, int lParam) -> LRESULT
{
	if(!(msg == WM_SYSKEYDOWN && wParam == VK_F4) && !wndproc::unfreeze_messages(hWnd, msg, wParam, lParam))
	{
		return false;
	}

	return ::CallWindowProcA(wndproc::original, hWnd, msg, wParam, lParam);
}

auto wndproc::unfreeze_messages(HWND hWnd, unsigned int msg, unsigned int wParam, int lParam) -> bool
{
	static bool bMoving{};
	static POINT ptOffset{};
	static LRESULT nLastSpot{};

	const auto on_release_capture = [hWnd]() -> void
	{
		if(nLastSpot == HTCLOSE)
		{
			::PostQuitMessage(EXIT_SUCCESS);
			bMoving = false;
			::ReleaseCapture();

			return;
		}

		else if(nLastSpot == HTMAXBUTTON)
		{
			::CallWindowProcA(wndproc::original, hWnd, WM_SYSCOMMAND, SC_MAXIMIZE, 0);

			return;
		}

		else if(nLastSpot == HTMINBUTTON)
		{
			::ShowWindow(hWnd, SW_MINIMIZE);

			return;
		}

		bMoving = false;
		::ReleaseCapture();
	};

	const auto drag_window = [hWnd]() -> void
	{
		if((::GetAsyncKeyState(VK_LBUTTON) & 0x8000) != 0)
		{
			if(bMoving)
			{
				POINT ptCursor;
				::GetCursorPos(&ptCursor);
				::SetWindowPos(hWnd, nullptr, ptCursor.x - ptOffset.x, ptCursor.y - ptOffset.y, 0, 0, SWP_NOSIZE | SWP_NOZORDER);
			}
		}

		else if(bMoving)
		{
			bMoving = false;
			::ReleaseCapture();
		}
	};

	const auto drag_title_bar = [hWnd]() -> void
	{
		if(nLastSpot == HTCAPTION)
		{
			RECT rcWnd;
			::GetWindowRect(hWnd, &rcWnd);

			POINT ptCursor;
			::GetCursorPos(&ptCursor);
			ptOffset.x = ptCursor.x - rcWnd.left;
			ptOffset.y = ptCursor.y - rcWnd.top;

			::SetCapture(hWnd);
			bMoving = true;
		}
	};

	switch(msg)
	{
	case WM_NCMOUSEMOVE:
		nLastSpot = wParam;
		break;

	case WM_MOUSEMOVE:
		nLastSpot = HTCLIENT;
		drag_window();
		break;

	case WM_LBUTTONUP:
	case WM_NCLBUTTONUP:
		on_release_capture();
		break;

	case WM_NCLBUTTONDOWN:
		drag_title_bar();
		[[fallthrough]];

	case WM_NCRBUTTONDOWN:
	case WM_NCRBUTTONUP:
		return false;

	case WM_RBUTTONUP:
		return !bMoving;
	}

	return true;
}