Arnisoft

FlexBuilder3 is based on Eclipse 3.3.1 and doesn’t work unfortunately with Eclipse 3.4.1 “Ganymede”.
But Eclipse “Ganymede” has a feature for easy integration of plugins called “dropins”, therefore under Eclipse 3.4.1 exist a “dropin” folder…

Close Eclipse and copy the complete Flexbuilder folder (standalone or plugin) inside this “dropin” folder. Restart Eclipse and now you should have the complete Flexbuilder envoirenment available!
Flexbuilder can be found with the default installation path at C :\Program Files\Adobe.