Bugfix/124 arguments tooltip regression second attempt

Source/ExcelDna.IntelliSense/IntelliSenseServer.cs

@@ -30,7 +30,7 @@ namespace ExcelDna.IntelliSense
     // REMEMBER: COM events are not necessarily safe macro contexts.
     public static class IntelliSenseServer
     {
-        const string ServerVersion = "1.7.0";  // TODO: Define and manage this somewhere else
+        const string ServerVersion = "1.7.1";  // TODO: Define and manage this somewhere else
 
         // NOTE: Do not change these constants in custom versions. 
         //       They are part of the co-operative safety mechanism allowing different add-ins providing IntelliSense to work together safely.

Source/ExcelDna.IntelliSense/UIMonitor/WinEvents.cs

@@ -219,6 +219,7 @@ bool IsSupportedWinEvent(WinEvent winEvent)
                    winEvent == WinEvent.EVENT_SYSTEM_MOVESIZESTART ||   // Only for the on-demand hook
                    winEvent == WinEvent.EVENT_SYSTEM_MOVESIZEEND ||   // Only for the on-demand hook
                    winEvent == WinEvent.EVENT_OBJECT_SELECTION ||           // Only for the PopupList
+                   winEvent == WinEvent.EVENT_OBJECT_LOCATIONCHANGE ||
                    winEvent == WinEvent.EVENT_SYSTEM_CAPTURESTART;
         }
 

Source/ExcelDna.IntelliSense/UIMonitor/WindowLocationWatcher.cs

@@ -9,39 +9,81 @@ public class WindowLocationWatcher : IDisposable
         IntPtr _hWnd;
         SynchronizationContext _syncContextAuto;
         SynchronizationContext _syncContextMain;
-        WinEventHook _windowLocationChangeHook;
+        WinEventHook _windowMoveSizeHook;
+        WinEventHook _locationChangeEventHook;
 
         public event EventHandler LocationChanged;
 
         // NOTE: An earlier attempt was to monitor LOCATIONCHANGE only between EVENT_SYSTEM_MOVESIZESTART and EVENT_SYSTEM_MOVESIZEEND
+        //       (for the purpose of moving the tooltip to the correct position when the user moves the Excel main window)
         //       This nearly worked, and meant we were watching many fewer events ...
         //       ...but we missed some of the resizing events for the window, leaving our tooltip stranded.
-        //       So until we can find a workaround for that (perhaps a timer would work fine for this), we watch all the LOCATIONCHANGE events.
+        //       We then started to watch all the LOCATIONCHANGE events, but it caused the Excel main window to lag when dragging.
+        //       (This drag issue seems to have been introduced with an Office update around November 2022)
+        //       So until we can find a workaround for that (perhaps a timer would work fine for this), we decided not to bother
+        //       with tracking the tooltip position (we still update it as soon as the Excel main window moving ends).
+        //       We still need to watch the LOCATIONCHANGE events, otherwise the tooltip is not shown at all in some cases.
+        //       To workaround the Excel main window lagging, we unhook from LOCATIONCHANGE upon encountering EVENT_SYSTEM_MOVESIZESTART
+        //       and then hook again upon encountering EVENT_SYSTEM_MOVESIZEEND (see UnhookFromLocationChangeUponDraggingExcelMainWindow).
         public WindowLocationWatcher(IntPtr hWnd, SynchronizationContext syncContextAuto, SynchronizationContext syncContextMain)
         {
             _hWnd = hWnd;
             _syncContextAuto = syncContextAuto;
             _syncContextMain = syncContextMain;
-            _windowLocationChangeHook = new WinEventHook(WinEventHook.WinEvent.EVENT_SYSTEM_MOVESIZESTART, WinEventHook.WinEvent.EVENT_SYSTEM_MOVESIZEEND, _syncContextAuto, syncContextMain, _hWnd);
-            _windowLocationChangeHook.WinEventReceived += _windowLocationChangeHook_WinEventReceived;
+            _windowMoveSizeHook = new WinEventHook(WinEventHook.WinEvent.EVENT_SYSTEM_MOVESIZESTART, WinEventHook.WinEvent.EVENT_SYSTEM_MOVESIZEEND, _syncContextAuto, syncContextMain, _hWnd);
+            _windowMoveSizeHook.WinEventReceived += _windowMoveSizeHook_WinEventReceived;
+
+            SetUpLocationChangeEventListener();
         }
 
-        void _windowLocationChangeHook_WinEventReceived(object sender, WinEventHook.WinEventArgs winEventArgs)
+        void SetUpLocationChangeEventListener()
+        {
+
+            _locationChangeEventHook = new WinEventHook(WinEventHook.WinEvent.EVENT_OBJECT_LOCATIONCHANGE, WinEventHook.WinEvent.EVENT_OBJECT_LOCATIONCHANGE, _syncContextAuto, _syncContextMain, IntPtr.Zero);
+            _locationChangeEventHook.WinEventReceived += _windowMoveSizeHook_WinEventReceived;
+        }
+
+        // This allows us to temporarily stop listening to EVENT_OBJECT_LOCATIONCHANGE events when the user is dragging the Excel main window.
+        // Otherwise we are going to bump into https://github.com/Excel-DNA/IntelliSense/issues/123. The rest of the time we need to stay
+        // hooked to EVENT_OBJECT_LOCATIONCHANGE for IntelliSense to work correctly (see https://github.com/Excel-DNA/IntelliSense/issues/124).
+        void UnhookFromLocationChangeUponDraggingExcelMainWindow(WinEventHook.WinEventArgs e)
+        {
+            if (e.EventType == WinEventHook.WinEvent.EVENT_SYSTEM_MOVESIZESTART)
+            {
+                _syncContextMain.Post(_ => _locationChangeEventHook?.Dispose(), null);
+            }
+
+            if (e.EventType == WinEventHook.WinEvent.EVENT_SYSTEM_MOVESIZEEND)
+            {
+                _syncContextMain.Post(_ => SetUpLocationChangeEventListener(), null);
+            }
+        }
+
+        void _windowMoveSizeHook_WinEventReceived(object sender, WinEventHook.WinEventArgs winEventArgs)
         {
 #if DEBUG
             Logger.WinEvents.Verbose($"{winEventArgs.EventType} - Window {winEventArgs.WindowHandle:X} ({Win32Helper.GetClassName(winEventArgs.WindowHandle)} - Object/Child {winEventArgs.ObjectId} / {winEventArgs.ChildId} - Thread {winEventArgs.EventThreadId} at {winEventArgs.EventTimeMs}");
 #endif
+
+            UnhookFromLocationChangeUponDraggingExcelMainWindow(winEventArgs);
+
             LocationChanged?.Invoke(this, EventArgs.Empty);
         }
 
         // Runs on the Main thread, perhaps during shutdown
         public void Dispose()
         {
             Debug.Assert(Thread.CurrentThread.ManagedThreadId == 1);
-            if (_windowLocationChangeHook != null)
+            if (_windowMoveSizeHook != null)
+            {
+                _windowMoveSizeHook.Dispose();
+                _windowMoveSizeHook = null;
+            }
+
+            if (_locationChangeEventHook != null)
             {
-                _windowLocationChangeHook.Dispose();
-                _windowLocationChangeHook = null;
+                _locationChangeEventHook.Dispose();
+                _locationChangeEventHook = null;
             }
         }
     }

Source/ExcelDna.IntelliSense/UIMonitor/WindowWatcher.cs

@@ -69,6 +69,10 @@ internal WindowChangedEventArgs(IntPtr windowHandle, WinEventHook.WinEvent winEv
                     case WinEventHook.WinEvent.EVENT_OBJECT_FOCUS:
                         Type = ChangeType.Focus;
                         break;
+                    case WinEventHook.WinEvent.EVENT_OBJECT_LOCATIONCHANGE:
+                        Type = ChangeType.LocationChange;
+                        ObjectId = ChangeObjectId.Caret;
+                        break;
                     case WinEventHook.WinEvent.EVENT_SYSTEM_MOVESIZEEND:
                         Type = ChangeType.LocationChange;
                         break;
@@ -113,6 +117,9 @@ internal WindowChangedEventArgs(IntPtr windowHandle, WinEventHook.WinEvent winEv
         const string _nuiDialogClass = "NUIDialog";
         const string _selectDataSourceTitle = "Select Data Source";     // TODO: How does localization work?
 
+        readonly SynchronizationContext _syncContextAuto;
+        readonly SynchronizationContext _syncContextMain;
+
         List<WinEventHook> _windowStateChangeHooks = new List<WinEventHook>();
 
         // These track keyboard focus for Windows in the Excel process
@@ -134,6 +141,9 @@ internal WindowChangedEventArgs(IntPtr windowHandle, WinEventHook.WinEvent winEv
 
         public WindowWatcher(SynchronizationContext syncContextAuto, SynchronizationContext syncContextMain)
         {
+            _syncContextAuto = syncContextAuto;
+            _syncContextMain = syncContextMain;
+
 #pragma warning disable CS0618 // Type or member is obsolete (GetCurrentThreadId) - But for debugging we want to monitor this anyway
             // Debug.Print($"### WindowWatcher created on thread: Managed {Thread.CurrentThread.ManagedThreadId}, Native {AppDomain.GetCurrentThreadId()}");
 #pragma warning restore CS0618 // Type or member is obsolete
@@ -151,8 +161,6 @@ public WindowWatcher(SynchronizationContext syncContextAuto, SynchronizationCont
             //  EVENT_OBJECT_SELECTIONREMOVE
             //  EVENT_OBJECT_SELECTIONWITHIN
             //  EVENT_OBJECT_STATECHANGE (0x800A = 32778)
-            // NB: Including the next event 'EVENT_OBJECT_LOCATIONCHANGE (0x800B = 32779)' will cause the Excel main window to lag when dragging.
-            // This drag issue seems to have been introduced with an Office update around November 2022.
             _windowStateChangeHooks.Add(new WinEventHook(WinEventHook.WinEvent.EVENT_OBJECT_CREATE, WinEventHook.WinEvent.EVENT_OBJECT_STATECHANGE, syncContextAuto, syncContextMain, IntPtr.Zero));
             _windowStateChangeHooks.Add(new WinEventHook(WinEventHook.WinEvent.EVENT_SYSTEM_CAPTURESTART, WinEventHook.WinEvent.EVENT_SYSTEM_CAPTURESTART, syncContextAuto, syncContextMain, IntPtr.Zero));
 
@@ -220,6 +228,7 @@ void _windowStateChangeHook_WinEventReceived(object sender, WinEventHook.WinEven
             {
                 Debug.Fail("WinEvent with window 0!?");
             }
+
             if (e.EventType == WinEventHook.WinEvent.EVENT_OBJECT_FOCUS)
             {
                 // Might raise change event for Unfocus