strange change of the indention to 3 spaces

[nilamo]

def foo():
"""spam"""
    a=0
    for n in range(10):
        a+=n
    return a

*edit* Ok, so you have to actually save for the change to happen. If you just go into Full Edit, the indentation is off, but if you cancel the edit without saving, it's still 4 spaces.
Seems like the Full Editor might be whack.