[mattmillus]

Thanks Garkin!

But how do you know the function isnt used, have you looked at this case in the past? Seems odd that the entire itemtooltips.lua file would be unused, unless its a work in progress for gamepad support or something..?

Is a prehook like follows your preferred method?
ZO_PreHookHandler(ItemTooltip, 'OnShow',function (control) onTooltipShow(control) end)
ZO_PreHookHandler(ItemTooltip, 'OnHide', function (control) onTooltipHide(control) end)

EDIT:
Is the entire ZO_Tooltip class unused? How do I get a handle to objects of this class? It is not the same as the global ItemTooltip control