I think that when somebody installs v6 alongside v5 that v6 should run
exclusively and not use v5 libraries.
I say this because when I installed v6 it wanted to use my old v5 libraries.
I copied my projects and libraries to entirely new directories so that my
old ones would not get fouled up and I made the appropriate changes to the
control panel "Options Directories", but Eagle IGNORED my changes that
pointed to the v6 libraries. Instead of using my v6 libraries, Eagle v6
continued to use my old v5 libraries from a non-specified directory.
Fortunately I realized that my old libraries were in use and proceeded to
fix the problem.
"Use -*" (enter) and then "Use *" took care of the problem, but WHY should
that rigamarole be necessary??.
This is not a suggestion so much as it is a bug report. It's an accident
waiting to happen. I remember the exact thing happening as I upgraded from
v4 to v5.