Start menu keyboard hotkey fix for Win11 Insider (#1165)

Windows 11 Insider builds started to register global shell hotkey for
Win key (and Ctrl+Esc) that are used to trigger start menu.

The problem is that it is not (easily) possible to intercept messages
about these hotkeys.

Thus we will unregister them during init and install hook that will
prevent their further registration.

Fixes #1165

Src/StartMenu/StartMenuDLL/StartMenuDLL.cpp

@@ -2853,6 +2853,34 @@ static BOOL WINAPI SetWindowCompositionAttribute2( HWND hwnd, WINCOMPATTRDATA *p
 	return SetWindowCompositionAttribute(hwnd,pAttrData);
 }
 
+///////////////////////////////////////////////////////////////////////////////
+// hooks for preventing shell hotkeys registration on Win11
+
+using ShellRegisterHotKey_t = BOOL(WINAPI*)(HWND, int, UINT, UINT, HWND);
+
+static IatHookData* g_ShellRegisterHotKeyHook;
+static ShellRegisterHotKey_t g_ShellRegisterHotKey;
+
+static BOOL WINAPI ShellRegisterHotKeyHook(HWND hWnd, int id, UINT fsModifiers, UINT vk, HWND hWndTarget)
+{
+	// Win key
+	if (fsModifiers == MOD_WIN && vk == 0)
+		return FALSE;
+
+	// Ctrl+Esc
+	if (fsModifiers == MOD_CONTROL && vk == VK_ESCAPE)
+		return FALSE;
+
+	return g_ShellRegisterHotKey(hWnd, id, fsModifiers, vk, hWndTarget);
+}
+
+// one-time APC function to unregister shell hotkeys
+void NTAPI DisableShellHotkeysFunc(ULONG_PTR Parameter)
+{
+	UnregisterHotKey(NULL, 1);
+	UnregisterHotKey(NULL, 2);
+}
+
 ///////////////////////////////////////////////////////////////////////////////
 
 static void OpenCortana( void )
@@ -2951,8 +2979,33 @@ static void InitStartMenuDLL( void )
 	g_ProgHook=SetWindowsHookEx(WH_GETMESSAGE,HookProgManThread,NULL,progThread);
 	g_StartHook=SetWindowsHookEx(WH_GETMESSAGE,HookDesktopThread,NULL,GetCurrentThreadId());
 	if (IsWin11())
+	{
 		g_StartMouseHook=SetWindowsHookEx(WH_MOUSE,HookDesktopThreadMouse,NULL,GetCurrentThreadId());
 
+		// hook ShellRegisterHotKey to prevent twinui.dll to install shell hotkeys (Win, Ctrl+Esc)
+		// without these hotkeys there is standard WM_SYSCOMMAND+SC_TASKLIST sent when start menu is invoked by keyboard shortcut
+		g_ShellRegisterHotKey = (ShellRegisterHotKey_t)GetProcAddress(GetModuleHandle(L"user32.dll"), MAKEINTRESOURCEA(2671));
+		auto twinui = GetModuleHandle(L"twinui.dll");
+
+		if (g_ShellRegisterHotKey && twinui)
+		{
+			g_ShellRegisterHotKeyHook = SetIatHook(twinui, "user32.dll" ,MAKEINTRESOURCEA(2671), ShellRegisterHotKeyHook);
+
+			// unregister shell hotkeys as they may be registered already
+			// this has to be done from context of thread that registered them
+			auto hwnd = FindWindow(L"ApplicationManager_ImmersiveShellWindow", NULL);
+			if (hwnd)
+			{
+				auto thread = OpenThread(THREAD_SET_CONTEXT, FALSE, GetWindowThreadProcessId(hwnd, NULL));
+				if (thread)
+				{
+					QueueUserAPC(DisableShellHotkeysFunc, thread, 0);
+					CloseHandle(thread);
+				}
+			}
+		}
+	}
+
 	HWND hwnd=FindWindow(L"OpenShellMenu.CStartHookWindow",L"StartHookWindow");
 	LoadLibrary(L"StartMenuDLL.dll"); // keep the DLL from unloading
 	if (hwnd) PostMessage(hwnd,WM_CLEAR,0,0); // tell the exe to unhook this hook
@@ -3150,6 +3203,8 @@ static void CleanStartMenuDLL( void )
 	g_DrawThemeTextCtlHook=NULL;
 	ClearIatHook(g_SetWindowCompositionAttributeHook);
 	g_SetWindowCompositionAttributeHook=NULL;
+	ClearIatHook(g_ShellRegisterHotKeyHook);
+	g_ShellRegisterHotKeyHook=NULL;
 
 	CloseManagers(false);
 	ClearIatHooks();