I'm having the same problem that maxsilver described. I'm running the Mac Steam version of Avadon, v1.0.4s, with the editor files (both basic and deluxe) in the Resources folder of the Avadon app package, but when I try either trigger (talk to a guard in Redbeard's tower, or clicking on the sign in Goldcrag), I get the "normal" dialog and not the editor.
My Resources folder currently has the following files in it:
avitemschars.txt
shortcut.icns
z2redtowerdlg.txt
z3goldcragdlg.txt
My Steam installation may be atypical; I was an early adopter of Steam for the Mac, and somehow I have it set so that Steam installs apps to my desktop rather than library/application support/steam (there's no such location on my computer).
I'm sure I'm overlooking something obvious, but I'm pretty new to modding so I'm hoping somebody can steer me in the right direction. Any advice would be appreciated!