I know, but you can use the buffdisplay out of your groupwindow to display them in a customwindow, making it effectively a 4th buffbar which you can move up right under the 3 hardcoded ones.
Found something like that for OchUI on the german boards:
>It only works grouped, since you don't see any buffs in your groupwindow if you don't have one.
>Some effects may not be shown in this bar (endurun, bodyguard).
>

ou can't remove buffs by using shift+rightclick in this window.
>

ou got to select the slot you're taking in your group to display the right buffs (your own ones, not someone else's

).
Screenshot:
http://www.vintersorg.de/custom/buff.bmp
DDL:
http://www.vintersorg.de/custom/X-Buffs.zip
Would be great if you could adapt it to GhostUI :>