is the choice window modified at all?
if it's the default script, then here
#== Snippet ==
class Window_ChoiceList < Window_Command
def initialize(message_window)
@message_window = message_window
super(0, 0)
self.openness = 0
deactivate
# change the 0 to any number you want, between 0 and 255
self.opacity = 0
# right here ^
end
end
#== snip ==
just place it above main and stuff