[Haleth]

Override bar works perfectly for me, no taint.

For shapeshift bar, I've modified Tukz's code a little so it shows/hides with override bar.

local function updateShift()
	local numForms = GetNumShapeshiftForms()
	local texture, name, isActive, isCastable
	local button, icon, cooldown
	local start, duration, enable
	for i = 1, NUM_STANCE_SLOTS do
		buttonName = "FreeUIStanceButton"..i
		button = _G[buttonName]
		icon = _G[buttonName.."Icon"]
		if i <= numForms then
			texture, name, isActive, isCastable = GetShapeshiftFormInfo(i)
			icon:SetTexture(texture)

			cooldown = _G[buttonName.."Cooldown"]
			if texture then
				cooldown:SetAlpha(1)
			else
				cooldown:SetAlpha(0)
			end

			start, duration, enable = GetShapeshiftFormCooldown(i)
			CooldownFrame_SetTimer(cooldown, start, duration, enable)

			if isActive then
				StanceBarFrame.lastSelected = button:GetID()
				button:SetChecked(1)
			else
				button:SetChecked(0)
			end

			if isCastable then
				icon:SetVertexColor(1.0, 1.0, 1.0)
			else
				icon:SetVertexColor(0.4, 0.4, 0.4)
			end
		end
	end
end

local shiftbar = CreateFrame("Frame", "FreeUI_StanceBar", UIParent, "SecureHandlerStateTemplate")
shiftbar:SetWidth(NUM_STANCE_SLOTS * 27 - 1)
shiftbar:SetHeight(26)
shiftbar:SetPoint("BOTTOMLEFT", UIParent, "BOTTOMLEFT", 50, 4)
shiftbar.buttons = {}
shiftbar:SetAttribute("_onstate-show", [[
	if newstate == "hide" then
		self:Hide();
	else
		self:Show();
	end
]])

shiftbar:RegisterEvent("PLAYER_LOGIN")
shiftbar:RegisterEvent("PLAYER_ENTERING_WORLD")
shiftbar:RegisterEvent("UPDATE_SHAPESHIFT_FORMS")
shiftbar:RegisterEvent("UPDATE_SHAPESHIFT_USABLE")
shiftbar:RegisterEvent("UPDATE_SHAPESHIFT_COOLDOWN")
shiftbar:RegisterEvent("UPDATE_SHAPESHIFT_FORM")
shiftbar:RegisterEvent("ACTIONBAR_PAGE_CHANGED")
shiftbar:SetScript("OnEvent", function(self, event, ...)
	if event == "PLAYER_LOGIN" then
		for i = 1, NUM_STANCE_SLOTS do
			if not self.buttons[i] then
				self.buttons[i] = CreateFrame("CheckButton", format("FreeUIStanceButton%d", i), self, "StanceButtonTemplate")
				self.buttons[i]:SetID(i)
			end
			local button = self.buttons[i]
			button:ClearAllPoints()
			button:SetParent(self)
			button:SetSize(26, 26)
			button:SetFrameStrata("LOW")
			if i == 1 then
				button:SetPoint("BOTTOMLEFT", shiftbar, 0, 0)
			else
				local previous = _G["FreeUIStanceButton"..i-1]
				button:SetPoint("LEFT", previous, "RIGHT", 3, 0)
			end
			local _, name = GetShapeshiftFormInfo(i)
			if name then
				button:Show()
			else
				button:Hide()
			end
		end
		RegisterStateDriver(self, "visibility", "[vehicleui] hide; show")
	elseif event == "UPDATE_SHAPESHIFT_FORMS" then
		if InCombatLockdown() then return end
		for i = 1, NUM_STANCE_SLOTS do
			local button = self.buttons[i]
			local _, name = GetShapeshiftFormInfo(i)
			if name then
				button:Show()
			else
				button:Hide()
			end
		end
	else
		updateShift()
	end
end)