XML comment fixes.

src/Avalonia.Base/Utilities/WeakEventHandlerManager.cs

@@ -19,6 +19,7 @@ namespace Avalonia.Utilities
         /// </summary>
         /// <typeparam name="TTarget">The type of the target.</typeparam>
         /// <typeparam name="TEventArgs">The type of the event arguments.</typeparam>
+        /// <typeparam name="TSubscriber">The type of the subscriber.</typeparam>
         /// <param name="target">The event source.</param>
         /// <param name="eventName">The name of the event.</param>
         /// <param name="subscriber">The subscriber.</param>
@@ -40,6 +41,7 @@ namespace Avalonia.Utilities
         /// Unsubscribes from an event.
         /// </summary>
         /// <typeparam name="TEventArgs">The type of the event arguments.</typeparam>
+        /// <typeparam name="TSubscriber">The type of the subscriber.</typeparam>
         /// <param name="target">The event source.</param>
         /// <param name="eventName">The name of the event.</param>
         /// <param name="subscriber">The subscriber.</param>

src/Avalonia.Controls/Window.cs

@@ -291,7 +291,8 @@ namespace Avalonia.Controls
         /// </summary>
         /// <param name="dialogResult">The dialog result.</param>
         /// <remarks>
-        /// When the window is shown with the <see cref="ShowDialog{TResult}"/> method, the
+        /// When the window is shown with the <see cref="ShowDialog{TResult}(IWindowImpl)"/>
+        /// or <see cref="ShowDialog{TResult}(Window)"/> method, the
         /// resulting task will produce the <see cref="_dialogResult"/> value when the window
         /// is closed.
         /// </remarks>

src/Avalonia.Styling/StyledElement.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using System.Collections.Specialized;
+using System.ComponentModel;
 using System.Linq;
 using System.Reactive.Linq;
 using System.Reactive.Subjects;