Ok now I actually read the code. I'm sure this error has something to do with right-click menu actions and keybind actions (they're implemented by the same class). This IGV_OnMouseEnter_postHook looks like it wraps the original handler, so that the original - which generates the list of actions - is now being called from add-on code (and those actions are mostly anonymous functions with add-on code in their closure now), making it ineligible to call protected functions directly.
Since this hook only needs to adjust tooltip placement, it should probably be done via customTooltipAnchor:
That tooltip anchor edit was the first to work in a long line of ideas. I just went with it when it started working
It looks like what you cooked up should work. Though, it seems like offsetX is always -4 which ultimately defeats the purpose of having a varying offset so that the tooltip always shows at the end of the row.
I'm too tired to mess with this now. I'll get back to it tomorrow.
Thanks again for the help!
Randactyl | NA Megaserver | Blood for the Pact!
Check out my GitHub repos to follow my latest changes and see some addons before they are released.