.tga is not transparent - .png is

[magges]

function Skada:ToggleWindow()
	for i, win in ipairs(windows) do
		if win:IsShown() then
			win.db.hidden = true
			win:Hide()
		else
			win.db.hidden = false
			win:Show()
		end
	end
end

i dont get how to use that in my addon :/

if i try to say for i, win ... win:Show() it wont work.
The same with ...then win.db.hidden = false
Do i have to set a some variables for the addon skada or ..whatever?