I wasn't sure where to post this, but I wrote a little bash script to make my mouse input ctrl+e only when purr-data is running.
In the hopes that this makes someone else's life a little easier, here's the script- you just need to bind it to your chosen mouse button using xbindkeys. (xbindkeys -k will pop open a little window where you can find out which button you're trying to assign, xev also works, but you'll need to download it as well) You'll also need to download xdotool if you don't have it already. I've included an xbindkeys config file as well.
note that you'll need to replace "purr-data" in the script at line S1='"purr-data"' with whatever the class of the windows are for the version of pd you're running. you can find this by running xprop in a terminal and clicking on pd, there should be a line with WM_CLASS. The text you want is what's in quotations after the third space in that line. The script will look for those quotation marks, so make sure you include them between the ticks!
If you're running purr-data and the button on your mouse you want to assign is somehow b:2, then this will work out of the box as long as you make the script executable and run xbindkeys -f /path/to/~xbindkeysrc
I know I've done a shoddy job explaining this, so please feel free to contact me if you want to get it working! I know it's saved me a lot of reaching to my keyboard when I'm disconnecting and connecting and testing things.~xbindkeysrc purr-data_editmodetoggle.sh