Adds a listener item to the WeakEventManager.ListenerList.
Assembly: WindowsBase (in WindowsBase.dll)
You should always call PrepareForWriting before changing the list contents. Otherwise, the list may be in process of delivering events and therefore the original is locked. Calling PrepareForWriting changes the input list to be a clone so that your call can still work on the clone. If PrepareForWriting returns true, you might need to update any private references to the list that you maintain in other areas of your code.
Windows 7, Windows Vista, Windows XP SP2, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003
The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.