It doesn't decrement the count, because it's inside a transaction that hasn't started yet..
It's all a bit fishy what answers you get back a files that you pending a transaction commit. the information is there inside the transaction, and would need much tighter coupling to get the correct answers.
But really, I think it was a mistake for the transaction actions to be created and queued within the 'real' methods - it should have been fully abstracted out of the actual superfile ops. - bit of a mess really.

Nevertheless prob. is clearer to test numSubFiles() before the removeSubFiles calls..
I'll change.