The current [alpha version][1] of Flex Builder on Linux doesn't have feature parity with the Windows and Mac versions of Flex Builder. It is scheduled to timeout on December 1, 2009 and current development [seems to be on hold][2]. If you would like to see Adobe create a full version of Flex Builder for Linux then please go vote for [feature request #FB-19053][3]! Thanks!

 [1]: http://labs.adobe.com/downloads/flexbuilder_linux.html
 [2]: http://gruchalski.com/2009/04/22/flex-builder-3-for-linux-on-hold/
 [3]: http://bugs.adobe.com/jira/browse/FB-19053