Teaser.js of Drupal6 blocks FCKEd from showing

I'm still new with D6 and recently I've made a fresh install of Drupal 6.11 from Debian package. I've noticed default content body textarea in Drupal 6 is enriched by a smaller textarea with a button that allows you to separate a teaser on the fly.

However this very textarea driven by Teaser.js turned out to be the reason that FCKEd didn't show up for me (it appeared at fields without teaser textarea). After I have manually disabled the code of Teaser.js everything was OK again.

The actual bug may very well be in Teaser.js - I'd only like to ask if there's a way to simply switch off this feature without manually hacking source files because I'm maintaining a site where everything is installed form packages and I want to avoid as much hacks as possible if I can just flip some variable in install profile.

Something related was reported in http://drupal.org/node/336517 but it seems the patch is still not applied to Drupal core.

Thanks