As much as I like using the terminal when making changes to the system I like a GUI application.
To that end I like using meld for comparing files and wanted to use this for pacdiff instead of vim. I never really used vim, I like nano and jed but that's it.
Anyway, pacdiff is a script which any root user can edit, and changing vim -d to meld works perfectly.
the line to change needs to look like this
Save and run the script as normal with