Take-snapshot is a project mainly written in JAVASCRIPT and ACTIONSCRIPT, it's free.
utility for taking snapshots of a flex application
A utility for taking snapshots from within your flex application. There are desktop snapshot tools available, but this one allows you take snapshots for scrolled container too.
Adds a context menu item that upon selection will present you with a dialog allowing to choose the ui element you want to snapshot.
Add the lib to the compiler arguments of the application that you'd like to have the functionality on.
eg: in your .actionscriptProperties add:
additionalCompilerArguments="-locale en_US -load-config+=additionalCompilerArguments.xml -include-libraries=${path_to_libs}\take-snapshot.swc"