Hi Pete
I can confirm the 4.6.1.6 beta is working as described.
I have a setup using SquawkBox4 and FSX-Acceleration on different PC's with SimConnect only between them (no WideFS). I did the test with the Piper PA31T2 Cheyenne IIXL. It is equipped with 2 Transponders with mode switches. In FS9 the mode switches did control the SB3 transponder. In FSX they do not.
So, I assigned the "Xpndr toggle (sb4)" control to a yoke toggle switch. The SB transponder window now shows the switching between STDBY and NORM properly. I also performed a verification test online on VATSIM and it worked as expected.
I hope a similar clever solution will be possible in the future for the "PTT" pushbutton I have on my yoke.
Thank you for devlivering solutions. FSUIPC, My best "investment" so far.
Paul