Great work on v4 @BrianTee_Admin. 
I see you have upped the number of sections to 15, any chance of increasing to say 24 (number of drill metering units on my drill!)?
Fully aware of the manual control issue, as you say I’m not going to be selecting sections manually on the move but the computer in auto is good at that.
How about having the option of assigning more than 1 section to each button. This would reduce the number of buttons needed on the screen. It would also make it more practical for manual control. AgOpenGPS could still control each individual section in auto mode.
It actually has 16 sections. ugh 24. That’s a lot of gui!
Not sure how to do the multiple sections per button, that would be tricky. If you have 24 sections it is unlikely you would be using the buttons anyway. At least with this individual way, you can turn one on/off if desired.
I think there is a better way beyond 16 and that is a default size for all of them. It gets far too complex to be able the individual size of 24 sections when its most likely a sprayer or planter with fixed distance anyway. most the challenge with going beyond 16 is all the code just to make them configurable for width.
Default size sounds good, if it can run as option to selecting size on the 16 as the code is now?
Perhaps as @SK21 said grouping into buttons.
With the existing code the way it is, that would be quite difficult to group them
If the problem is because of the buttons and it is not possible to group them as @SK21 said, it would not be possible to create a Window(form) to turn the sections on and off manually.
Today its one page with setup for width of sections. maybe 16 of each side and a side change button?
Arduino side with setup of IO ports pr section do i think we need to use shift register instead of one IO port pr section, then its no limit of channels.
UDP packet does not support over 16 channels today. Maybe use the first byte to tell shift register index and the second to define the channels? Then will the limit be 2048 channels (Lucky the man that should wire that)
On the GUI when driving will i say no one can control above 8 sections manual. So if we activate over 16 sections the manual control can be disabled.