Address review: quote template path and use full explorer.exe path

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

src/settings-ui/Settings.UI.UnitTests/ViewModelTests/NewPlus.cs

@@ -0,0 +1,34 @@
+// Copyright (c) Microsoft Corporation
+// The Microsoft Corporation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System;
+using System.Diagnostics;
+using System.IO;
+using System.Reflection;
+
+using Microsoft.PowerToys.Settings.UI.ViewModels;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+
+namespace ViewModelTests
+{
+    [TestClass]
+    public class NewPlus
+    {
+        [TestMethod]
+        public void CreateExplorerProcessStartInfoShouldQuoteTemplatePathAndUseFullExplorerPath()
+        {
+            // Arrange
+            const string templatePath = @"C:\Users\Test User\Documents\My Templates";
+            var createExplorerProcessStartInfoMethod = typeof(NewPlusViewModel).GetMethod("CreateExplorerProcessStartInfo", BindingFlags.NonPublic | BindingFlags.Static);
+
+            // Act
+            var processStartInfo = (ProcessStartInfo)createExplorerProcessStartInfoMethod.Invoke(null, new object[] { templatePath });
+
+            // Assert
+            Assert.IsNotNull(processStartInfo);
+            Assert.AreEqual(Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.Windows), "explorer.exe"), processStartInfo.FileName);
+            Assert.AreEqual($"\"{templatePath}\"", processStartInfo.Arguments);
+        }
+    }
+}

src/settings-ui/Settings.UI/ViewModels/NewPlusViewModel.cs

@@ -330,6 +330,8 @@ namespace Microsoft.PowerToys.Settings.UI.ViewModels
             }
         }
 
+        private static readonly string ExplorerExePath = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.Windows), "explorer.exe");
+
         private bool _isNewPlusEnabled;
         private string _templateLocation;
         private bool _hideFileExtension;
@@ -356,12 +358,7 @@ namespace Microsoft.PowerToys.Settings.UI.ViewModels
             {
                 CopyTemplateExamples(_templateLocation);
 
-                var process = new ProcessStartInfo()
-                {
-                    FileName = _templateLocation,
-                    UseShellExecute = true,
-                };
-                Process.Start(process);
+                Process.Start(CreateExplorerProcessStartInfo(_templateLocation));
             }
             catch (Exception ex)
             {
@@ -369,6 +366,15 @@ namespace Microsoft.PowerToys.Settings.UI.ViewModels
             }
         }
 
+        private static ProcessStartInfo CreateExplorerProcessStartInfo(string templateLocation)
+        {
+            return new ProcessStartInfo
+            {
+                FileName = ExplorerExePath,
+                Arguments = $"\"{templateLocation}\"",
+            };
+        }
+
         private async void PickNewTemplateFolder()
         {
             var newPath = await PickFolderDialog();