#665 Unsynchronized methods in AttachmentModel

[Jay Zuckerman]

The class
"org.columba.mail.gui.message.viewer.AttachmentModel"
contains synchronized methods for setting two of its
fields,
"setFolder()" and "setUid()".

However the corresponding "getFolder" and "getUid"
fields are not synchronized, which could lead to
inconsistent behaviors at runtime if multiple threads
can observe different object states. These two methods
should be made synchronized.

I have attached a modified version of
AttachmentModel.java with the methods made synchronized.

[Jay Zuckerman]

Attachment Model with synchronized get() methods