WowAce

This doesn't seem to work on a new configuration.  The mob database can't populate because unit GUIDs went through a big change in 6.0.  The local DB may need another way to index mobs; I'm not sure the new GUIDs have a reusable component in them.

https://wow.gamepedia.com/API_UnitGUID

I looked into DBM's code and found something to can (presumably) pull some constant, unique info from the GUID and use that.  I can now populate the mob list within a zone, but as soon as I hover over a list item I get AceGUI errors.  At that point I'm lost.

I'll also say I'm trying to use this in Classic.  I made two other changes; 1) zone difficulty is never heroic and 2) using "AttemptToSaveBindings" instead of "SaveBindings".

2x ...nfig-3.0\AceConfigDialog-3.0\AceConfigDialog-3.0-78.lua:189: attempt to index local 'option' (a nil value)
...nfig-3.0\AceConfigDialog-3.0\AceConfigDialog-3.0-78.lua:189: in function <...nfig-3.0\AceConfigDialog-3.0\AceConfigDialog-3.0.lua:169>
...nfig-3.0\AceConfigDialog-3.0\AceConfigDialog-3.0-78.lua:1504: in function <...nfig-3.0\AceConfigDialog-3.0\AceConfigDialog-3.0.lua:1483>
[C]: ?
...aceBartender4\libs\AceGUI-3.0\AceGUI-3.0-40.lua:72: in function <...aceBartender4\libs\AceGUI-3.0\AceGUI-3.0.lua:70>
...aceBartender4\libs\AceGUI-3.0\AceGUI-3.0-40.lua:290: in function `Fire'
...ibs\AceGUI-3.0-40\widgets\AceGUIContainer-TreeGroup.lua:208: in function <...ibs\AceGUI-3.0\widgets\AceGUIContainer-TreeGroup.lua:206>

You're doing God's work, sir! I used to absolutely  LOVE this addon. I think it was within my top 3 addons ever.  I loved being able to sweep my mouse over a pack of mobs in a raid and mark them accordingly.  It's just beautiful.   I really hope someone can update this.