i can't seem to make TrailGlow to follow the Character when i'm moving with the 8Direction behavior not with the mouse.
That's because most behaviors -- 8 Direction included -- update before events are processed. Set OldX and OldY after all of the trail events -- at the end of the event sheet, for example -- and things will work. As it stands now, the flow of actions is:
Update 8-Direction behavior -> Set OldX, OldY -> Update trail, Result: OldX and OldY equal the actual position when the trail is updated, thus, no trail.
Whereas updating afterwards yields:
Update 8-DIrection behavior -> Update trail -> Set OldX, OldY, Result: OldX and OldY are different from the actual position when the trail is updated since they were updated at the end of the previous frame.