app: clamp the flyout position to the monitor it is anchored on

The window's bottom-right was placed at the tray anchor with no bounds
check, so it landed at (-1136,-875) on a two-monitor desktop -- entirely
off both screens, while the tray still reported the app as open and the
only way back was Task Manager.

Any anchor near a top or left edge does it: the taskbar can be moved,
the icon may live in the overflow flyout, a secondary monitor can sit at
negative coordinates, and the window can be taller than the screen it is
anchored on. Clamp into the work area of the monitor under the anchor,
preferring the TOP-LEFT to stay visible when the window is larger than
that area, and log the anchor/size/result so an off-screen placement is
diagnosable from the log instead of from a missing window.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: Ryanmello07

app/src/App/AppController.cpp

@@ -3,6 +3,7 @@
 
 #include "AppController.h"
 
+#include <algorithm>
 #include <string_view>
 
 #include <winrt/Microsoft.UI.Windowing.h>
@@ -259,8 +260,36 @@ void AppController::ShowWindowImpl(const POINT* anchor) {
       auto appWindow = winrt::Microsoft::UI::Windowing::AppWindow::GetFromWindowId(windowId);
       auto size = appWindow.Size();
       // place the window's bottom-right near the tray icon (bottom-right corner)
-      winrt::Windows::Graphics::PointInt32 pos{anchor->x - size.Width,
-                                               anchor->y - size.Height};
+      int x = anchor->x - size.Width;
+      int y = anchor->y - size.Height;
+
+      // ...then clamp into the WORK AREA of the monitor the anchor is on, or
+      // the window lands where nobody can see it. Unclamped, this put the
+      // window at (-1136,-875) on a two-monitor desktop -- entirely off both
+      // screens, with the tray still saying the app was open. Every anchor
+      // near a top or left edge does it: the taskbar is not always bottom
+      // right (it can be moved, and the icon may live in the overflow flyout),
+      // a secondary monitor can sit at negative coordinates, and the window
+      // can be taller than the screen it is anchored on. MONITOR_DEFAULTTONEAREST
+      // keeps a bogus anchor on a real monitor rather than failing.
+      POINT anchorPt{anchor->x, anchor->y};
+      HMONITOR mon = ::MonitorFromPoint(anchorPt, MONITOR_DEFAULTTONEAREST);
+      MONITORINFO mi{};
+      mi.cbSize = sizeof(mi);
+      if (mon && ::GetMonitorInfoW(mon, &mi)) {
+        const RECT& work = mi.rcWork;
+        // max() after min() so a window larger than the work area still has
+        // its TOP-LEFT on screen (the title bar and close button) rather than
+        // its bottom-right
+        x = (std::max)(static_cast<long>(work.left),
+                       (std::min)(x, work.right - size.Width));
+        y = (std::max)(static_cast<long>(work.top),
+                       (std::min)(y, work.bottom - size.Height));
+      }
+
+      winrt::Windows::Graphics::PointInt32 pos{x, y};
+      LogInfo("app: window anchor ({},{}) size {}x{} -> position ({},{})",
+              anchor->x, anchor->y, size.Width, size.Height, pos.X, pos.Y);
       appWindow.Move(pos);
     }
   }