What is a "Freezable" subtype in WPF/Silverlight?

Question

What is a "Freezable" subtype in WPF/Silvellight?

Answer 1

Ripped straight from MSDN's Freezable Objects Overview:

The Freezable class makes it easier to use certain graphics system objects and can help improve application performance. Examples of types that inherit from Freezable include the Brush, Transform, and Geometry classes. Because they contain unmanaged resources, the system must monitor these objects for modifications, and then update their corresponding unmanaged resources when there is a change to the original object. Even if you don't actually modify a graphics system object, the system must still spend some of its resources monitoring the object, in case you do change it.

Answer 2

A freezable object is one that has a mechanism that allows you to "Freeze" it. This locks downs all the state and makes the object immutable. This makes the object more performant to use and safer to share between threads.

http://msdn.microsoft.com/en-us/library/ms750509.aspx

Answer 3

Important thing. Silverlight doesn't contains Freezable or FreezableCollection in it's infrastructure.

http://msdn.microsoft.com/en-us/library/cc903925(VS.95).aspx

http://www.charlespetzold.com/blog/2008/11/Text-on-a-Path-in-Silverlight.html