Microsoft has just released the Silverlight 4 RC with several changes in the
Silverlight runtime & in the Silverlight tools. Though there are couple of
changes since Silverlight 3 & since Silverlight 4 Beta but it supports most
of the Silverlight 3 applications by using Quirks mode. In some cases your
earlier application will break or behave differently.
In this post I will
describe you both the breaking changes in Silverlight 4 since Silverlight 3
& Silverlight 4 Beta. But before going to the discussion on the breaking
changes, let me tell you what is Quirks mode. Quirks mode is a behaviour by
which your previous application will work on the new runtime. Simple example is
that, if you have Silverlight 3 compiled application it will try to run in
Silverlight 4 (some cases it will fail) using quirks mode but if you compile the
same application in Silverlight 4 it will not use the quirks mode and through
errors on the changes.
What's new in Silverlight
- XAP Signing
- Custom Chrome Window
- WebCam/Mic Configuration Preview
- Text position and Selection API
- Pinned full screen mode on secondary display
- Support for Private Browsing
- RichTextBox XAML clipboard format
- Elevated apps doesn't have Sockets Security Restrictions
- Support for querying printer page size and printable area
- XmlnsPrefix & XmlnsDefinition attributes has been added
Breaking Changes since Silverlight
So, lets start with describing the breaking changes in
Silverlight 4 since Silverlight 3.
- Mouse Wheel Support - Silverlight 4 controls (ListBox,
TextBox, ComboBox, ScrollViewer, Calendar, DatePicker, DataGrid) now have
support for Mouse Wheel.
- Shared BitmapImage Source - Now Silverlight 4 will render
the images properly if more than one Image controls are sharing the same
- ImageBrush.ImageSource returns ImageSource -
ImageBrush.ImageSource in Silverlight 4 now returns ImageSource instead of
UriSource which could be WritableBitmap or BitmapImage.
- Keyboard Navigation in TabControl - Keyboard navigation in
TabControl was a feature in Silverlight 3 having an issue with the TabItem
activation. Previously pressing Up Arrow activated the next TabItem and pressing
Down Arrow activated the previous TabItem. In this release they fixed it to
properly activate the TabItem. In Silverlight 4 if you press Up Arrow it will
activate the previous TabItem & pressing Down Arrow will activate the next
- Automation focus in DataGridCell - DataGridCell now
receives automation focus when currency changes in the DataGrid, rather than
focusing on the other part of the DataGrid.
- Hit Test while Toggling Full Screen Mode - While toggling
full screen mode Silverlight 4 will now rerun hit testing. This allows controls
that were under the mouse before toggling to update the MoouseEnter state if
- Whitespace handling with Span tag - TextBlock and
RichTextArea now accepts text content & creates implicit runs generating
whitespaces between inlines separated by CRLF.
- DisplayMemberPath & ItemTemplate recreates all
containers - Silverlight 4 now recreates all containers by invalidating
them while there is any change in DisplayMemberPath or in ItemTemplate
properties of the ItemControl.
- New XAML Parser - Silverlight 4 now includes all new XAML
Parser along with the previous XAML Parser. As per the runtime version detected
in the application manifest it will parse the XAML in the appropriate parser.
Apart from that, it has now additional benefits like "Better XAML
compatibility", "Greater parsing correctness & consistency", "Better
feedback error mechanism", "Performance improvement".
- Panels Clear() method calls InvalidateMeasure - If you call
the Clear() method of the Silverlight 4 panel it will now explicitly call
- Virtualizing Stack Panel now scrolls by 3 lines - Mouse
Wheel scroll in Silverlight 4's Virtualizing Stack Panel will scroll by three
(3) lines instead of one (1) line.
since Silverlight 4 Beta:
If you were exploring Silverlight 4
Beta this section will be most important for you. There are some changes in both
the runtime & tool since the beta release. So before starting with that
please read the same carefully.
- Removed TextSelection.CanInsert - TextSelection.CanInsert
is now no longer available in Silverlight 4.
- RichTextArea changed to RichTextBox - RichTextArea now
renamed to RichTextBox.
- RichTextBox.TextDecorations no longer exists -
RichTextBox.TextDecoration is not available now. Instead of it you can use
- Default value to RichTextBox.TextWrapping - Silverlight 4
now has a default value of RichTextBox.TextWrapping to Wrap. If you don't want
to wrap your content you have to explicitly set it to NoWrap.
- HtmlBrush renamed to WebBrowserBrush - In Silverlight 4
HtmlBrush now renamed to WebBrowserBrush.
- COM Interoperability - COM Interoperability types are now
moved to System.Runtime.InteropServices instead of System.Windows.Interop
- WebCam/Output Protection Support - There has been a huge
changes in the webcam/output protection support:
- CanEnableHDCP renamed to CanEnableHdcp
- CanEnableCGMSA renamed to CanEnableCgmsa
- VGA, DVI, HDMI, LVDS, SDI, UDIExternal, UDIInternal also renamed to similar
- VideoFormat.Height and VideoFormat.Width renamed to VideoFormat.PixelHeight
and VideoFormat.PixelWidth respectively
- AsyncCaptureImage call now changed to CaptureImageAsync
- NotificationWindow - NotificationWindow.Visible property
has been changed to NotificationWindow.Visibility
This post only tells about the breaking changes in Silverlight 4 RC. I will go forward to publish new articles with samples on those changes in Silverlight 4 RC. So, keep an eye to this forum.