UIElement.HitTest method has moved to the VisualTreeHelper class and has been renamed to VisualTreeHelper.FindElementsInHostCoordinates.
Moved DependencyPropertyChangedEventHandler delegate type from System.Windows.Controls to System.Windows namespace.
Control.IsTabStop defaults to true. Now, all Control derived classes (directly or indirectly) have IsTabStop set to true except, UserControl, HyperlinkButton, ScrollViewer and ListBox.
WebHeaderCollection.Keys property was replaced with the AllKeys property.
WebHeaderCollection.Headers property was renamed to Keys.
WebRequest.RegisterPrefix() no returns false in failure cases per the interface contract from the desktop framework rather than throwing an exception.
WebResponse.Dispose(bool explicitDisposing) was removed.
Deployment.PartProperty is now read only.
Deployment.EntryPointAssemblyProperty is now read only.
Deployment.EntryPointTypeProperty is now read only.
Deployment.RuntimeVersionProperty is now read only.
Deployment.ExternalCallersFromCrossDomainProperty is now read only.
Thumb.IsDragging is now read only.
Slider.IsFocused is now read only.
ButtonBase.IsFocused is now read only.
ButtonBase.IsMouseOver is now read only.
ButtonBase.IsPressed is now read only.
ToolTipService.GetToolTip is now private.
IRawElementProviderSimple is now sealed and has a private default constructor.
Setter.PropertyProperty is now internal. Please use the CLR property instead of the DependencyProperty.
Slider.UpdateTrackLayout() is now internal.
Slider.OnOrientationChanged() is now internal.
Slider.OnIsFocusChanged(DependencyPropertyChangedEventArgs e) is now internal.
ComboBox.get_IsSelectionActive() is now internal.
ComboBox.ScrollIntoView(Int32 index) is now internal.
ComboBox.get_SelectionBoxItemTemplate() now returns System.Windows.DataTemplate.
PasswordBox.SelectionChanged is now private.
MouseEventArgs.Handled was moved to MouseButtonEventArgs.
RenderTargetBitmap was renamed to HostingRenderTargetBitmap and moved from System.Windows.Media.Imaging to namespace System.Windows.Interop.
AutomationPeer constructor is now protected.
TriggerActionCollection.Item now takes System.Windows.TriggerAction instead of System.Windows.Media.Animation.BeginStoryboard.
TriggerCollection.Item now takes System.Windows.TriggerBase instead of System.Windows.EventTrigger.
RoutedEventArgs.Source was renamed to OriginalSource and is now read-only.
ITableItemProvider and ITableProvider are now derived from IGridItemProvider and IGridProvider.
The KeyboardNavigation class is now internal.
ColumnDefinitionCollection constructor was made internal.
InlineCollection constructor was made internal.
ItemCollection constructor was made internal.
RowDefinitionCollection constructor was made internal.
UIElementCollection constructor was made internal.
TriggerCollection constructor was made internal.
Listbox field ListBoxItem._itemsControl is now internal.
Ink.Stroke constructor changed to ctor(System.Windows.Input.StylusPointCollection).
CanConvertFrom(Type sourceType) changed its signature to CanConvertFrom(ITypeDescriptorContext context, Type sourceType).
CanConvertTo(Type destinationType) changed its signature to CanConvertTo(ITypeDescriptorContext context, Type destinationType).
ConvertFrom(object value) changed its signature to ConvertFrom(ITypeDescriptorContext context, CultureInfo culture, object value).
ConvertFromString(string text) now is ConvertFrom(ITypeDescriptorContext context, CultureInfo culture, object value) where value of type string.
ConvertTo(object value, Type destinationType) changed its signature to ConvertTo(ITypeDescriptorContext context, CultureInfo culture, object value, Type destinationType).
ConvertToString(object value) now is ConvertTo(ITypeDescriptorContext context, CultureInfo culture, object value, Type destinationType) with destinationType of type string.
ItemCollection constructor is no longer available so any code that tries to instantiate an ItemCollection directly will no longer compile. This class is supposed to be instantiated only within ItemsControl.
ContentPresenter now derives from FrameworkElement instead of Control.
Control.OnIsEnabledChanged was removed. Now use IsEnabledChanged for extended controls.
DownloadProgressEventHandler was removed.
The following converters were removed: