saw this with CVS build yesterday and new one now: Set pref to alternate 3-pane for mailnews. Start mailnews, select an account folder. Result: Right side of the vertical splitter looks wrong - the black line is too wide.
not a bug anymore. WFM.
Verified on Win 2000, Linux, Mac OSX on the recent branch build 2001-09-27. No need to verify on trunk.