Almost anyone using this list is probably going to be using
CVS or SVN with Flex rather than Visual SourceSafe, as they are
free. You can get plugins for Flex Builder/Eclipse that integrate
CVS or SVN source code control into your project. Many projects use
SVN now, and on Windows TortoiseSVN is frequently used as a context
menu based way of managing changes in your source code repository.
You can do some googling for 'eclipse svn plugin', or I
believe CVS is built-in by default, which you would see under
Window->Preferences->Team->CVS in eclipse/FB.