I have a 780 too and there is no VFO in it -- not in the same sense that a ham transceiver usually has a VFO "scratch pad." In the 780 you must program a frequency into a memory if you want to monitor it -- or you have to go to a mem freq and then tune up & down from it. It sounds like most users reserve a memory channel somewhere for temporary "VFO" use. Still not a great solution, it involves a lot of extra keypresses... but it's the best we can do.
This is definitely one of my least favorite things about the radio. I wish it had an AOR-style dual VFO.
73,
Matt