[Vrul]

Originally Posted by LudiusMaximus But I never see the print of my hook... Am I missing something?

That function runs before your code ever has a chance to hook it.

You need something like:

local function SetIgnoreParentAlpha(_, frame)
    frame:SetIgnoreParentAlpha(true)
end
 
for _, subSystem in pairs(AlertFrame.alertFrameSubSystems) do
    local pool = type(subSystem) == 'table' and subSystem.alertFramePool
    if type(pool) == 'table' and type(pool.resetterFunc) == 'function' then
        hooksecurefunc(pool, "resetterFunc", SetIgnoreParentAlpha)
    end
end

Here is an easy way to test it:

/run UIParent:SetAlpha(0.5); NewMountAlertSystem:ShowAlert("123")