Thank you for reading this.
Not long ago I remember reading, on this list, about someone running mmsstv under wine. I've had receive only capability for sometime but after recently receiving good sstv from Seeds my interest in transmitting sstv has been reawakened.
I have the extfsk dll installed in the same directory as mmsstv and its dialogue box opens to show that the ptt is on during transmit, however, the transmitter is not keyed. The port option in mmsstv is set to extfsk.
The extfsk dialogue box has a status indicator the reads "Status:NG". This possibly means "no good". The status reads the same under Windows, so the problem may not be specific to Linux and wine.
By the way, the rts line does key the transmitter while using native linux applications.