This seems to be related to bug http://sourceforge.net/tracker/index.php?func=detail&aid=1281410&group_id=75859&atid=545274
When using the options 'use spaces instead of tabs', pressing 'TAB' will give the requested number of spaces, but the auto-indent after a curly bracket still gives a real TAB, at least in 0.6.3.1
Heiko