Some games do not allow to save before switching discs. When one of those games is played from a iso file, only the first cd can be played.
Can you tell me at least one game where this happens and provide a save-game? It should be possible to add this feature. Thank you for the request.
Added in CVS - hit F9 to 'open the lid', and be prompted to specify the BIN image to load, and F10 to 'close the lid' and continue.
Updated gui/Plugins.c to support this. Tested successfully with G-Police with both dfIso and dfBinImage plugins.
Note that FF8 was not successful since the discs have to be patched to get past mod check; the game seems to detect these as invalid discs.