Just wanted to share here in case anyone else can benefit from my experience. I upgraded my civi drupal installation recently from Civi 4.2.6 to Civi LTS 4.4.19. Somehow the setting for sharing drupal's wysiwyg editor got lost. I don't know if that's a problem with the installation, or if there was some unique problem on my system. In any case, once I figured out what was going on, I just had to reset as per http://wiki.civicrm.org/confluence/display/CRMDOC/Configuring+CiviCRM+to+Use+the+Default+Drupal+Editor.
Also, FYI I see here that this setting is going away unless someone builds an extension. https://civicrm.org/blogs/colemanw/big-changes-wysiwyg-editing-47