Convert a regular string to a fake Edit Field text
This should put theString$ into a new edit field type of handle named TextHndl&. I think this is what you want.
theString$ = "The file you want to save to is: DataFile"
strLen& = LEN(theString$)
TextHndl& = FN NEWHANDLE _Clear(strLen& + 2)
LONG IF TextHndl& > 0
osErr = FN HLOCK (TextHndl&)
POKE WORD [TextHndl&], strLen&
BLOCKMOVE @theString$, [TextHndl&] + 2, strLen&
osErr = FN HUNLOCK (TextHndl&)