Create a window process for the tray icon

src/cascadia/WindowsTerminal/TrayIcon.cpp

@@ -23,6 +23,32 @@ TrayIcon::~TrayIcon()
     RemoveIconFromTray();
 }
 
+void TrayIcon::_CreateWindow()
+{
+    WNDCLASSW wc{};
+    wc.hCursor = LoadCursor(nullptr, IDC_ARROW);
+    wc.hInstance = wil::GetModuleInstanceHandle();
+    wc.lpszClassName = L"TRAY_ICON_HOSTING_WINDOW_CLASS";
+    wc.style = CS_HREDRAW | CS_VREDRAW;
+    wc.lpfnWndProc = DefWindowProcW;
+    wc.hIcon = static_cast<HICON>(GetActiveAppIconHandle(true));
+    RegisterClass(&wc);
+
+    _trayIconHwnd = wil::unique_hwnd(CreateWindowW(wc.lpszClassName,
+                                                   wc.lpszClassName,
+                                                   WS_DISABLED,
+                                                   CW_USEDEFAULT,
+                                                   CW_USEDEFAULT,
+                                                   CW_USEDEFAULT,
+                                                   CW_USEDEFAULT,
+                                                   HWND_MESSAGE,
+                                                   nullptr,
+                                                   wc.hInstance,
+                                                   nullptr));
+
+    WINRT_VERIFY(_trayIconHwnd);
+}
+
 // Method Description:
 // - Creates and adds an icon to the notification tray.
 // If an icon already exists, update the HWND associated
@@ -33,6 +59,15 @@ TrayIcon::~TrayIcon()
 // - <none>
 void TrayIcon::CreateTrayIcon()
 {
+    if (!_trayIconHwnd)
+    {
+        // Creating a disabled, non visible window just so we can set it
+        // as the foreground window when showing the context menu.
+        // This is done so that the context menu can be dismissed
+        // when clicking outside of it.
+        _CreateWindow();
+    }
+
     NOTIFYICONDATA nid{};
     nid.cbSize = sizeof(NOTIFYICONDATA);
 
@@ -81,7 +116,7 @@ void TrayIcon::ShowTrayContextMenu(const til::point coord,
     {
         // We'll need to set our window to the foreground before calling
         // TrackPopupMenuEx or else the menu won't dismiss when clicking away.
-        SetForegroundWindow(_owningHwnd);
+        SetForegroundWindow(_trayIconHwnd.get());
 
         // User can select menu items with the left and right buttons.
         UINT uFlags = TPM_RIGHTBUTTON;

src/cascadia/WindowsTerminal/TrayIcon.h

@@ -30,8 +30,10 @@ class TrayIcon
     WINRT_CALLBACK(SummonWindowRequested, winrt::delegate<void(winrt::Microsoft::Terminal::Remoting::SummonWindowSelectionArgs)>);
 
 private:
+    void _CreateWindow();
     HMENU _CreateTrayContextMenu(winrt::Windows::Foundation::Collections::IMapView<uint64_t, winrt::hstring> peasants);
 
+    wil::unique_hwnd _trayIconHwnd;
     HWND _owningHwnd;
     NOTIFYICONDATA _trayIconData;
 };