I came across this phenomenon whilst experimenting with button code to drive Select SOURCETODEST and Select DESTTOSOURCE commands. See [url=Select items in Dest]
I often work with a single lister on my laptop display and another single lister on an extended desktop display. At any point in time, the active lister could be Source or Dest, hence my interest in making sure I get the comparison the right way round. The Set DEST=Toggle is typically a prelude to a Select ALL and another Set DEST=Toggle.
Regards, AB