[Peek]Prevent activation when user is typing (#33299)

* prevent Peek activation when user is typing

* fix spellcheck

.github/actions/spell-check/expect.txt

@@ -149,6 +149,7 @@ Cangjie
 CANRENAME
 CAPTUREBLT
 CAPTURECHANGED
+CARETBLINKING
 CAtl
 cch
 CCHDEVICENAME

src/modules/peek/Peek.UI/Helpers/FileExplorerHelper.cs

@@ -3,12 +3,14 @@
 // See the LICENSE file in the project root for more information.
 
 using System;
+using System.Runtime.InteropServices;
 using Peek.Common.Models;
 using Peek.UI.Extensions;
 using SHDocVw;
 using Windows.Win32;
 using Windows.Win32.Foundation;
 using Windows.Win32.UI.Shell;
+using Windows.Win32.UI.WindowsAndMessaging;
 using IServiceProvider = Peek.Common.Models.IServiceProvider;
 
 namespace Peek.UI.Helpers
@@ -27,7 +29,12 @@ namespace Peek.UI.Helpers
 
         private static IShellItemArray? GetItemsInternal(HWND foregroundWindowHandle, bool onlySelectedFiles)
         {
-            if (foregroundWindowHandle.IsDesktopWindow())
+            // If the caret is visible, we assume the user is typing and we don't want to interfere with that
+            if (CaretVisible(foregroundWindowHandle))
+            {
+                return null;
+            }
+            else if (foregroundWindowHandle.IsDesktopWindow())
             {
                 return GetItemsFromDesktop(foregroundWindowHandle, onlySelectedFiles);
             }
@@ -104,5 +111,21 @@ namespace Peek.UI.Helpers
 
             return null;
         }
+
+        /// <summary>
+        /// Returns whether the caret is visible in the specified window.
+        /// </summary>
+        private static bool CaretVisible(HWND hwnd)
+        {
+            GUITHREADINFO guiThreadInfo = new() { cbSize = (uint)Marshal.SizeOf<GUITHREADINFO>() };
+
+            // Get information for the foreground thread
+            if (PInvoke.GetGUIThreadInfo(0, ref guiThreadInfo))
+            {
+                return guiThreadInfo.hwndActive == hwnd && (guiThreadInfo.flags & GUITHREADINFO_FLAGS.GUI_CARETBLINKING) != 0;
+            }
+
+            return false;
+        }
     }
 }

src/modules/peek/Peek.UI/NativeMethods.txt

@@ -19,4 +19,5 @@ GetWindowRect
 SET_WINDOW_POS_FLAGS
 SetWindowPos
 GetWindowPlacement
-SetWindowPlacement
+SetWindowPlacement
+GetGUIThreadInfo