Once again I herded my ragtag group of secondaries into the room with the primary. Firing up Multiplicity on each, I began with my duties, and once again I encountered strange behavior... certainly not what I was expecting! Then, once again it came to me: because I'm left-handed and have my mouse on the left side of the computer, I have the buttons reversed. My primary button is the right. And Multiplicity is incapable of dealing with that. It's hard-coded to assume the left button. And so when I'm using the right button as primary button on the primary computer, Multiplicity is interpreting that as the secondary button on all my secondary computers.

Once again I go around to each secondary computer, open Settings (using the left, or secondary button on my primary computer, so that it will be interpreted as the primary on the secondary computer) open "Mouse" (using the left, or secondary button on my primary computer, so that it will be interpreted as the primary on the secondary computer), and click on "Select your primary button" (using the left, or secondary button on my primary computer, so that it will be interpreted as the primary on the secondary computer). Now at last I can use the right button as primary on the primary computer and it will be interpreted as such by Multiplicity.

Well, no, Multiplicity isn't actually doing any interpreting. It's just going its old hard-coded self on blindly.

Now, once again repeat the above sequence for each of the other secondaries.

Hard-coded. In 2020. Wow.