Added TokenItemRemoved events

Author: shweaver-MSFT

Microsoft.Toolkit.Uwp.UI.Controls.Input/TokenizingTextBox/TokenizingTextBox.Properties.cs

@@ -170,9 +170,16 @@ private static void OnTokenSelectionModeChanged(DependencyObject d, DependencyPr
         {
             if (d is TokenizingTextBox ttb && e.NewValue is TokenSelectionMode newTokenSelectionMode && newTokenSelectionMode == TokenSelectionMode.Single)
             {
-                while (ttb.Items.Count > 1)
+                // Start at the end, remove all but the first token.
+                for (var i = ttb._innerItemsSource.Count - 1; i >= 1; --i)
                 {
-                    ttb.Items.RemoveAt(ttb.Items.Count - 1);
+                    var item = ttb._innerItemsSource[i];
+                    if (item is not ITokenStringContainer)
+                    {
+                        // Force remove the items. No warning and no option to cancel.
+                        ttb._innerItemsSource.Remove(item);
+                        ttb.TokenItemRemoved?.Invoke(ttb, item);
+                    }
                 }
             }
         }

Microsoft.Toolkit.Uwp.UI.Controls.Input/TokenizingTextBox/TokenizingTextBox.cs

@@ -450,13 +450,15 @@ internal async Task AddTokenAsync(object data, bool? atEnd = null)
 
             if (TokenSelectionMode == TokenSelectionMode.Single)
             {
-                // Remove any existing tokens.
+                // Start at the end, remove any existing tokens.
                 for (var i = _innerItemsSource.Count - 1; i >= 0; --i)
                 {
                     var item = _innerItemsSource[i];
                     if (item is not ITokenStringContainer)
                     {
+                        // Force remove the items. No warning and no option to cancel.
                         _innerItemsSource.Remove(item);
+                        TokenItemRemoved?.Invoke(this, item);
                     }
                 }
             }