Hrmmm.. I'm not sure what Lock Text Area means.
You can look on msdn.microsoft.com, under (let's see if I remember right) User Interface->Controls->Individual Controls->Edit Controls->Edit Controls Reference->Messages to see a list of edit control (textarea) messages.
You can look on msdn.microsoft.com, under (let's see if I remember right) User Interface->Controls->Individual Controls->Edit Controls->Edit Controls Reference->Messages to see a list of edit control (textarea) messages.