Keep Tray UI test window live off-screen (#897)

Move the WinUI UI-test fixture window off-screen instead of hiding it with SW_HIDE so XamlRoot remains attached for layout smoke tests in CI.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Author: shanselman

tests/OpenClaw.Tray.UITests/UIThreadFixture.cs

@@ -226,9 +226,9 @@ private void UIThreadProc()
 
                     if (!IsSlow)
                     {
-                        // Default: hide the window so CI runs are silent.
-                        _startupPhase = "hiding test window";
-                        TryHide(TestWindow);
+                        // Default: keep the window live but off-screen so CI runs are silent.
+                        _startupPhase = "moving test window off-screen";
+                        MoveOffScreen(TestWindow);
                     }
 
                     _startupPhase = "ready";
@@ -248,17 +248,14 @@ private void UIThreadProc()
         }
     }
 
-    private static void TryHide(Window w)
+    private static void MoveOffScreen(Window w)
     {
         try
         {
-            // WindowsAppSDK 1.5+ supports AppWindow.Hide via WinUIEx, but to keep
-            // deps minimal we just move the window off-screen. It's still a real
-            // Window — XamlRoot is attached, the visual tree lays out — but the
-            // user never sees it during tests.
-            var hwnd = WinRT.Interop.WindowNative.GetWindowHandle(w);
-            // SW_HIDE = 0
-            ShowWindow(hwnd, 0);
+            // Move off-screen so CI runs are silent while keeping the window
+            // live in the WinUI compositor. XamlRoot stays attached, the visual
+            // tree lays out, but the user never sees it during tests.
+            w.AppWindow.MoveAndResize(new Windows.Graphics.RectInt32(-32000, -32000, 1, 1));
         }
         // slopwatch-ignore: SW003 Test cleanup or fixture teardown is best-effort and must not hide the test outcome.
         catch
@@ -267,10 +264,6 @@ private static void TryHide(Window w)
         }
     }
 
-    [System.Runtime.InteropServices.DllImport("user32.dll")]
-    [return: System.Runtime.InteropServices.MarshalAs(System.Runtime.InteropServices.UnmanagedType.Bool)]
-    private static extern bool ShowWindow(IntPtr hWnd, int nCmdShow);
-
     public void Dispose()
     {
         try