[lerb]

Thanks for the hints unlimit. I did what you said, but still there seems to be something I'm missing. To make it simple, I tried using this code;

local function SkinGrid()
    local GridFrame = Grid and Grid:GetModule("GridFrame")
    if GridFrame and GridFrame.registeredFrames then
        -- print("Adding borders to Grid frames")
        
        local function Grid_AddBorder(f)
            CreateBorderLight(frame, LeUI.media.bordersize, LeUI.bordercolor, LeUI.bordercolor, LeUI.bordercolor, 2)
        end
        
        hooksecurefunc(GridFrame, "RegisterFrame", function(frame)
            Grid_AddBorder(f)
        end)
 
        return true
    end
end
 
if not SkinGrid() then
    local f = CreateFrame("Frame")
    f:RegisterEvent("ADDON_LOADED")
    f:RegisterEvent("PLAYER_LOGIN")
    f:SetScript("OnEvent", function()
        if SkinGrid() then
            f:UnregisterAllEvents()
            f:SetScript("OnEvent", nil)
            SkinGrid = nil
        end
    end)
end

Sadly, that doesn't do anything. I'm not sure about how hooksecurefunc works, but I'm guessing out of the blue that this code is something like this; "When grid spawns a new frame, this hooksecurefunc 'senses' it and fires my Grid_AddBorder function, which is a command that tells !beautycase to add a border to the frame spawned by grid".

Please, correct me if I'm wrong. Which I probably am