Does IsolatedStorageFileStream.Lock work under SIlverlight4?

Question

Silverlight uses an IsolatedStorageFileStream to open files.

The IsolatedStorageFileStreamunder NET.4 claims to support the Lock Method (Inherited from FileStream)

The following code

IsolatedStorageFile isf;
IsolatedStorageFileStream lockStream = new IsolatedStorageFileStream( "my.lck", FileMode.OpenOrCreate, isf );
lockStream.Lock( 0, 0 );

generates the following error, wrapped for readability, under VS2010 and Silverlight 4

'System.IO.IsolatedStorage.IsolatedStorageFileStream' does not contain a definition for 'Lock' 
and no extension method 'Lock' accepting a first argument of type 'System.IO.IsolatedStorage.IsolatedStorageFileStream' could be found 
(are you missing a using directive or an assembly reference?)   

Answer 1

Lock and Unlock are not actually supported but are present so that the System.IO.FileStream classes are consistent between frameworks and allows for the feature to be implemented in the future.