This thread has a similar problem but with a parent file, but the principles are no different.
This link has a toolbar method, which does similar. You would need to track down the toolbar event thats being posted, and I think the one Lee posted is what would help.
In essence instead of mimicking the user with a presskey, this is using an event which does similar, ie it posts an event:scrollbottom to the windows accept loop. I dont have my computer on so Im going from a rapidly fading memory.