[plt-scheme] auto completion of function names etc in drscheme

Hi,
I've been recently trying out drscheme (version 300, on a debian AMD64 
machine), and one thing which i can't manage to find is auto completion 
of symbols - e.g. write partial name - press "tab" - get a list of 
possible completions.
I have tried googling the mailing list archive (and just the web in 
general), and searched the manuals / help desk, but I can't seem to find 
anything.
Am I missing something obvious?
thanks,
niv