Make sure to call base methods in Button

src/Avalonia.Controls/Button.cs

@@ -309,6 +309,8 @@ namespace Avalonia.Controls
                 IsPressed = false;
                 e.Handled = true;
             }
+
+            base.OnKeyUp(e);
         }
 
         /// <summary>
@@ -393,6 +395,8 @@ namespace Avalonia.Controls
         /// <inheritdoc/>
         protected override void OnPointerCaptureLost(PointerCaptureLostEventArgs e)
         {
+            base.OnPointerCaptureLost(e);
+
             IsPressed = false;
         }
 
@@ -407,6 +411,8 @@ namespace Avalonia.Controls
         /// <inheritdoc/>
         protected override void OnApplyTemplate(TemplateAppliedEventArgs e)
         {
+            base.OnApplyTemplate(e);
+
             UnregisterFlyoutEvents(Flyout);
             RegisterFlyoutEvents(Flyout);
             UpdatePseudoClasses();