Cancelling Accidentals

[Arthur Baum]

I have Lilypond 2.2.0. Is there a way to change key signatures in the middle 
of a piece (for example, from A major to E-flat major) without printing 
cancelling naturals?

I just want three flats to be engraved at the start of the new bar, but all 
I can get is three naturals followed by three flats. I saw Laura Conrad's 
post of 16 Sep 2002, but the suggestions given there don't seem to be 
working.

Is there a property we can set to turn off cancelling accidentals in the new 
key signature? If not, this would be a useful feature. Are there any other 
workarounds in the current version of Lilypond?

Thanks,


Art     =op