real time sequence change - which OS?

Hi Gents.
Someone mentioned before about flipping between sequences in real time, without the next sequence reverting to the start. ie, the clock keeps running the same, while you flip to a different sequence, then back again (if you want to.)
This doesn't seem to work on jjos 3.10, so I'm guessing it's a feature of one (or more) of the other versions.
could you tell me if that's the case, or where to look?

Thanks.

J