Upgrading Projects from Silverlight 4 to Silverlight 5
Several changes have been made to the Silverlight runtime and the Silverlight Tools between Silverlight 4 and Silverlight 5. For these changes, the following principles apply:
1- Most Silverlight 4 applications will work with Silverlight 5 without any changes.
2- When breaking changes are required, Silverlight will try to maintain support for the old behavior, as well as the new behavior, by using a quirks mode.
Nevertheless, some changes made to Silverlight components can potentially cause your older Silverlight-based applications to fail (compile time, XAML load time, or possibly design time) or to behave differently.
There are no known breaking changes between Silverlight 4 and Silverlight 5 in the Silverlight core runtime. Applications that were originally compiled using Silverlight 4 tools, and that continue to target the Silverlight 4 runtime, should work without issues on a client that has the Silverlight 5 runtime.
To retarget an existing Silverlight 4 project for the Silverlight 5 runtime specifically, you should change the project targeting in Visual Studio, using the Silverlight Build Options / Target Silverlight Version section of the Visual Studio project configuration dialog. Then, recompile the project.
Silverlight 5 Templates
The latest Silverlight templates are available in Silverlight Toolkit December 2011. This toolkit is the 9th release which is targeting the Silverlight 5’s new 3D features.
