WowAce

The game menu micro button is getting tainted, because it calls CloseMenus() which depends on UIMenus being secure.

Reference: https://www.townlong-yak.com/framexml/live/UIParent.lua#3699

I have already found a possible fix, in bold below.

-- //////////////////////////////////////////////////////////////
-- Handling two frames from LibUIDropDownMenu.xml
local function create_DropDownButtons()
 L_DropDownList1 = creatre_DropDownList("L_DropDownList1")
 L_DropDownList1:SetToplevel(true)
 L_DropDownList1:SetFrameStrata("FULLSCREEN_DIALOG")
 L_DropDownList1:Hide()
 L_DropDownList1:SetID(1)
 L_DropDownList1:SetSize(180, 10)
 local _, fontHeight, _ = _G["L_DropDownList1Button1NormalText"]:GetFont()
 L_UIDROPDOWNMENU_DEFAULT_TEXT_HEIGHT = fontHeight
 
 L_DropDownList2 = creatre_DropDownList("L_DropDownList2")
 L_DropDownList2:SetToplevel(true)
 L_DropDownList2:SetFrameStrata("FULLSCREEN_DIALOG")
 L_DropDownList2:Hide()
 L_DropDownList2:SetID(2)
 L_DropDownList2:SetSize(180, 10)

-- UIParent integration; since we customize the name of DropDownList, we need to add it to golbal UIMenus table.
 --tinsert(UIMenus, "L_DropDownList1");
 --tinsert(UIMenus, "L_DropDownList2");
 
 -- Alternative by Dahk Celes (DDC) that avoids tainting UIMenus and CloseMenus()
 hooksecurefunc("CloseMenus", function()
 L_DropDownList1:Hide()
 L_DropDownList2:Hide()
 end)
end

do
 if lib then 
 create_DropDownButtons()
 end
end

Thanks for the codes, this has been added to the new release.