Delay initializing the Backend submenu until the last possible moment.

Windows/MainWindow.cpp

@@ -970,9 +970,9 @@ namespace MainWindow
 			DestroyWindow(hWnd);
 			break;
 
-		case WM_MENUSELECT:
-			// Called when a menu is opened. Also when an item is selected, but meh.
-			UpdateMenus((HMENU)lParam);
+		case WM_INITMENUPOPUP:
+			// Called when a menu or submenu is about to be opened.
+			UpdateMenus((HMENU)wParam);
 			WindowsRawInput::NotifyMenu();
 			trapMouse = false;
 			break;

Windows/MainWindowMenu.cpp

@@ -63,6 +63,8 @@ extern bool g_TakeScreenshot;
 namespace MainWindow {
 	extern HINSTANCE hInst;
 	extern bool noFocusPause;
+	std::vector<HMENU> g_topLevelMenus;
+	HMENU g_hMenuBackend;
 
 	static std::unordered_map<int, std::string> initialMenuKeys;
 	static std::vector<std::string> availableShaders;
@@ -167,8 +169,11 @@ namespace MainWindow {
 		info.cyMax = 0;
 		info.dwStyle = MNS_CHECKORBMP;
 		info.fMask = MIM_STYLE;
+		g_topLevelMenus.clear();
 		for (int i = 0; i < GetMenuItemCount(hMenu); i++) {
-			SetMenuInfo(GetSubMenu(hMenu, i), &info);
+			HMENU subMenu = GetSubMenu(hMenu, i);
+			SetMenuInfo(subMenu, &info);
+			g_topLevelMenus.push_back(subMenu);
 		}
 
 		// Always translate first: translating resets the menu.
@@ -179,6 +184,9 @@ namespace MainWindow {
 		if (System_GetPropertyBool(SYSPROP_APP_GOLD)) {
 			RemoveMenu(helpMenu, ID_HELP_BUYGOLD, MF_BYCOMMAND);
 		}
+
+		HMENU hMenuOptions = GetSubmenuById(hMenu, ID_OPTIONS_MENU);
+		g_hMenuBackend = GetSubmenuById(hMenuOptions, ID_OPTIONS_BACKEND_MENU);
 	}
 
 	static void TranslateMenuItem(const HMENU hMenu, const int menuID, const std::wstring& accelerator = L"", const char *key = nullptr) {
@@ -988,8 +996,30 @@ namespace MainWindow {
 			vfpudlg->Show(false);
 	}
 
+	static void UpdateBackendSubMenu(HMENU menu);
+
 	void UpdateMenus(HMENU menuSelected) {
 		HMENU menu = GetMenu(GetHWND());
+
+		if (menuSelected) {
+			// Technically we only need to update the selected menu.
+			if (menuSelected == g_hMenuBackend) {
+				UpdateBackendSubMenu(menu);
+				return;
+			}
+			bool found = false;
+			for (auto topLevelMenu : g_topLevelMenus) {
+				if (menuSelected == topLevelMenu) {
+					found = true;
+				}
+			}
+
+			if (!found) {
+				// Don't do anything
+				return;
+			}
+		}
+
 #define CHECKITEM(item,value) 	CheckMenuItem(menu,item,MF_BYCOMMAND | ((value) ? MF_CHECKED : MF_UNCHECKED));
 		CHECKITEM(ID_DEBUG_IGNOREILLEGALREADS, g_Config.bIgnoreBadMemAccess);
 		CHECKITEM(ID_DEBUG_SHOWDEBUGSTATISTICS, (DebugOverlay)g_Config.iDebugOverlay == DebugOverlay::DEBUG_STATS);
@@ -1197,6 +1227,15 @@ namespace MainWindow {
 			CheckMenuItem(menu, savestateSlot[i], MF_BYCOMMAND | ((i == g_Config.iCurrentStateSlot) ? MF_CHECKED : MF_UNCHECKED));
 		}
 
+#if !PPSSPP_API(ANY_GL)
+		EnableMenuItem(menu, ID_DEBUG_GEDEBUGGER, MF_GRAYED);
+#endif
+
+		UpdateCommands();
+	}
+
+	// This one is pretty expensive so we handle it separately.
+	static void UpdateBackendSubMenu(HMENU menu) {
 		bool allowD3D11 = g_Config.IsBackendEnabled(GPUBackend::DIRECT3D11);
 		bool allowOpenGL = g_Config.IsBackendEnabled(GPUBackend::OPENGL);
 		bool allowVulkan = g_Config.IsBackendEnabled(GPUBackend::VULKAN);
@@ -1227,12 +1266,6 @@ namespace MainWindow {
 			CheckMenuItem(menu, ID_OPTIONS_VULKAN, MF_UNCHECKED);
 			break;
 		}
-
-#if !PPSSPP_API(ANY_GL)
-		EnableMenuItem(menu, ID_DEBUG_GEDEBUGGER, MF_GRAYED);
-#endif
-
-		UpdateCommands();
 	}
 
 	void UpdateCommands() {