I love Mirror, but it have a bug that was driving me crazy. It's not a Mirror's bug tbh, it's Blizzard fault to implement silly code, but nevertheless there's something wrong.
All works fine but when I visit a vendor. As soon as I open the trade window I get 2 "compare" tooltips (my rings) without touching anything. And without hovering over any item. So I have only the 2 "compare" tooltips. Moreover they are incredibly detailed, as the infos Auctioneer, bankitems, and other mods are appending to the tooltips are replicated by the number of items the vendor have in the window.
Ok, that's the bug, here's the explanation.
As soon as a trader window is opened for every item sold WoW creates a GameTooltip and launch a phantom event (idiotic idea, but that's it). The GameTooltip however have no Owner (GameTooltip:GetOwner() returns nil). It's just an initialization of the real GameTooltip the items will have in a few.
Solution: Mirror.lua, line 31 (about)
local tooltipOwner = GameTooltip:GetOwner()
--just in case there is no owner
if (tooltipOwner == nil) then
if tooltipOwner then
If I understand you correctly, when you open a merchant window, you get 2 compare tooltips popping up on the screen and no actual GameTooltip appearing. I, personally, could not replicate this behavior, but if that is the case, it seems that something else is hooking GameTooltip OnHide event improperly, because once that is fired, the compare tooltips (ShoppingTooltip1 and ShoppingTooltip2) should be hidden regardless. Try to determine what addon is making those tooltips appear and then we might be able to work out a solution.
The reason why I do not want to implement your fix is that it may cause the mod not work with some other mods that may be forgetting to set the Parent for a GameTooltip.