Since I don't have Flash Develop on my mac mini but I have plenty of space because I upgraded its hard disk, I thought it was a good moment to install Eclipse and use it at least for ActionScript3 -- although I'm quite tempted of doing the same for PHP stuff; the PHP Development Tools (PDT) plugin for Eclipse is gorgeous.
Anyway, I headed to Eclipse's website, downloaded the package, uncompressed to my /Applications folder. It worked, cool. I downloaded the Flex builder plug in, ran the installation program and discovered to my horror that instead of creating its own folder in the destination folder, it indeed used the destination folder for filling it with its myriad of files. Riiiiiight! There was an Uninstall Flex Builder Plugin.app file somewhere -- I saw that!
So I clicked it, waited for the uninstaller to finish... all good, my ~/Applications folder was clean again. Then I clicked again on the Flex Plug in installer and it asked me for my Eclipse folder... and I couldn't find it! Where is it!? Yes: if you uninstall the plugin, it uninstalls everything, including Eclipse.
Luckily I hadn't done anything interesting and in addition I think that the preferences are stored outside the Eclipse folder (somewhere in ~/Library probably). But this is just and plainly wrong, Adobe guys!
I might use Eclipse for something else than Flex, you need to understand it!