Hide the window from DWM until we're finished with initialization

src/cascadia/TerminalApp/TerminalPage.cpp

@@ -713,12 +713,21 @@ namespace winrt::TerminalApp::implementation
             // Switch to the BG thread -
             co_await winrt::resume_background();
 
-            // Then enqueue the rest of this function for after the UI thread settles.
-            co_await wil::resume_foreground(Dispatcher(), CoreDispatcherPriority::Low);
+            if (auto self{ weak.get() })
+            {
+                // Then enqueue the rest of this function for after the UI thread settles.
+                co_await wil::resume_foreground(self->Dispatcher(), CoreDispatcherPriority::Low);
+            }
+            else
+            {
+                // We don't exist anymore? Well, we probably don't need to fire
+                // off an Initialized event then...
+                co_return;
+            }
 
             if (auto self{ weak.get() })
             {
-                _InitializedHandlers(*self, nullptr);
+                self->_InitializedHandlers(*self, nullptr);
             }
         }
     }

src/cascadia/WindowsTerminal/AppHost.cpp

@@ -73,8 +73,7 @@ AppHost::AppHost() noexcept :
     auto pfn = std::bind(&AppHost::_HandleCreateWindow,
                          this,
                          std::placeholders::_1,
-                         std::placeholders::_2,
-                         std::placeholders::_3);
+                         std::placeholders::_2);
     _window->SetCreateCallback(pfn);
 
     _window->SetSnapDimensionCallback(std::bind(&winrt::TerminalApp::AppLogic::CalcSnappedDimension,
@@ -518,12 +517,31 @@ LaunchPosition AppHost::_GetWindowLaunchPosition()
     return pos;
 }
 
+// Method Description:
+// - Callback for when the window is first being created (during WM_CREATE).
+//   Stash the proposed size for later. We'll need that once we're totally
+//   initialized, so that we can show the window in the right position *when we
+//   want to show it*. If we did the _initialResizeAndRepositionWindow work now,
+//   it would have no effect, because the window is not yet visible.
+// Arguments:
+// - hwnd: The HWND of the window we're about to create.
+// - proposedRect: The location and size of the window that we're about to
+//   create. We'll use this rect to determine which monitor the window is about
+//   to appear on.
+void AppHost::_HandleCreateWindow(const HWND /* hwnd */, RECT proposedRect)
+{
+    // GH#11561: Hide the window until we're totally done being initialized.
+    // More commentary in TerminalPage::_CompleteInitialization
+    _proposedRect = proposedRect;
+}
+
 // Method Description:
 // - Resize the window we're about to create to the appropriate dimensions, as
-//   specified in the settings. This will be called during the handling of
-//   WM_CREATE. We'll load the settings for the app, then get the proposed size
-//   of the terminal from the app. Using that proposed size, we'll resize the
-//   window we're creating, so that it'll match the values in the settings.
+//   specified in the settings. This is called once the app has finished it's
+//   initial setup, once we have created all the tabs, panes, etc. We'll load
+//   the settings for the app, then get the proposed size of the terminal from
+//   the app. Using that proposed size, we'll resize the window we're creating,
+//   so that it'll match the values in the settings.
 // Arguments:
 // - hwnd: The HWND of the window we're about to create.
 // - proposedRect: The location and size of the window that we're about to
@@ -532,16 +550,8 @@ LaunchPosition AppHost::_GetWindowLaunchPosition()
 // - launchMode: A LaunchMode enum reference that indicates the launch mode
 // Return Value:
 // - None
-void AppHost::_HandleCreateWindow(const HWND hwnd, RECT proposedRect, LaunchMode& launchMode)
+void AppHost::_initialResizeAndRepositionWindow(const HWND hwnd, RECT proposedRect, LaunchMode& launchMode)
 {
-    // GH#11561: Hide the window until we're totally done being initialized.
-    // More commentary in TerminalPage::_CompleteInitialization
-    BOOL cloak = TRUE;
-    LOG_IF_FAILED(DwmSetWindowAttribute(hwnd,
-                                        DWMWA_CLOAK,
-                                        &cloak,
-                                        sizeof(cloak)));
-
     launchMode = _logic.GetLaunchMode();
 
     // Acquire the actual initial position
@@ -1560,11 +1570,18 @@ void AppHost::_CloseRequested(const winrt::Windows::Foundation::IInspectable& /*
 void AppHost::_AppInitializedHandler(const winrt::Windows::Foundation::IInspectable& /*sender*/,
                                      const winrt::Windows::Foundation::IInspectable& /*arg*/)
 {
-    // GH#11561: We're totally done being initialized. Uncloak the window, making it visible.
-    // More commentary in TerminalPage::_CompleteInitialization
-    BOOL cloak = FALSE;
-    LOG_IF_FAILED(DwmSetWindowAttribute(_window->GetHandle(),
-                                        DWMWA_CLOAK,
-                                        &cloak,
-                                        sizeof(cloak)));
+    // GH#11561: We're totally done being initialized. Resize the window to
+    // match the initial settings, and then call ShowWindow to finally make us
+    // visible.
+
+    LaunchMode launchMode{};
+    _initialResizeAndRepositionWindow(_window->GetHandle(), _proposedRect, launchMode);
+
+    int nCmdShow = SW_SHOW;
+    if (WI_IsFlagSet(launchMode, LaunchMode::MaximizedMode))
+    {
+        nCmdShow = SW_MAXIMIZE;
+    }
+
+    ShowWindow(_window->GetHandle(), nCmdShow);
 }

src/cascadia/WindowsTerminal/AppHost.h

@@ -31,6 +31,7 @@ class AppHost
 
     bool _shouldCreateWindow{ false };
     bool _useNonClientArea{ false };
+    RECT _proposedRect{};
 
     std::optional<til::throttled_func_trailing<>> _getWindowLayoutThrottler;
     winrt::Windows::Foundation::IAsyncAction _SaveWindowLayouts();
@@ -39,7 +40,7 @@ class AppHost
     void _HandleCommandlineArgs();
     winrt::Microsoft::Terminal::Settings::Model::LaunchPosition _GetWindowLaunchPosition();
 
-    void _HandleCreateWindow(const HWND hwnd, RECT proposedRect, winrt::Microsoft::Terminal::Settings::Model::LaunchMode& launchMode);
+    void _HandleCreateWindow(const HWND hwnd, RECT proposedRect);
     void _UpdateTitleBarContent(const winrt::Windows::Foundation::IInspectable& sender,
                                 const winrt::Windows::UI::Xaml::UIElement& arg);
     void _UpdateTheme(const winrt::Windows::Foundation::IInspectable&,
@@ -121,6 +122,9 @@ class AppHost
                                         const winrt::Windows::Foundation::IInspectable& args);
     void _HideNotificationIconRequested(const winrt::Windows::Foundation::IInspectable& sender,
                                         const winrt::Windows::Foundation::IInspectable& args);
+
+    void _initialResizeAndRepositionWindow(const HWND hwnd, RECT proposedRect, winrt::Microsoft::Terminal::Settings::Model::LaunchMode& launchMode);
+
     std::unique_ptr<NotificationIcon> _notificationIcon;
     winrt::event_token _ReAddNotificationIconToken;
     winrt::event_token _NotificationIconPressedToken;

src/cascadia/WindowsTerminal/IslandWindow.cpp

@@ -112,7 +112,7 @@ void IslandWindow::Close()
 //        window.
 // Return Value:
 // - <none>
-void IslandWindow::SetCreateCallback(std::function<void(const HWND, const RECT, LaunchMode& launchMode)> pfn) noexcept
+void IslandWindow::SetCreateCallback(std::function<void(const HWND, const RECT)> pfn) noexcept
 {
     _pfnCreateCallback = pfn;
 }
@@ -154,19 +154,13 @@ void IslandWindow::_HandleCreateWindow(const WPARAM, const LPARAM lParam) noexce
     rc.right = rc.left + pcs->cx;
     rc.bottom = rc.top + pcs->cy;
 
-    LaunchMode launchMode = LaunchMode::DefaultMode;
     if (_pfnCreateCallback)
     {
-        _pfnCreateCallback(_window.get(), rc, launchMode);
+        _pfnCreateCallback(_window.get(), rc);
     }
 
-    int nCmdShow = SW_SHOW;
-    if (WI_IsFlagSet(launchMode, LaunchMode::MaximizedMode))
-    {
-        nCmdShow = SW_MAXIMIZE;
-    }
-
-    ShowWindow(_window.get(), nCmdShow);
+    // GH#11561: DO NOT call ShowWindow here. The AppHost will call ShowWindow
+    // once the app has completed it's initialization.
 
     UpdateWindow(_window.get());
 

src/cascadia/WindowsTerminal/IslandWindow.h

@@ -37,7 +37,7 @@ class IslandWindow :
 
     virtual void Initialize();
 
-    void SetCreateCallback(std::function<void(const HWND, const RECT, winrt::Microsoft::Terminal::Settings::Model::LaunchMode& launchMode)> pfn) noexcept;
+    void SetCreateCallback(std::function<void(const HWND, const RECT)> pfn) noexcept;
     void SetSnapDimensionCallback(std::function<float(bool widthOrHeight, float dimension)> pfn) noexcept;
 
     void FocusModeChanged(const bool focusMode);
@@ -92,7 +92,7 @@ class IslandWindow :
     winrt::Windows::UI::Xaml::Controls::Grid _rootGrid;
     wil::com_ptr<ITaskbarList3> _taskbar;
 
-    std::function<void(const HWND, const RECT, winrt::Microsoft::Terminal::Settings::Model::LaunchMode& launchMode)> _pfnCreateCallback;
+    std::function<void(const HWND, const RECT)> _pfnCreateCallback;
     std::function<float(bool, float)> _pfnSnapDimensionCallback;
 
     void _HandleCreateWindow(const WPARAM wParam, const LPARAM lParam) noexcept;