API Frame CreateLine

Here is an example drawing a red default thickness (4) line diagonally:

local f = CreateFrame("Frame") f:SetPoint("CENTER", 0, 100) f:SetSize(100,100) local l = f:CreateLine print(l) l:SetColorTexture(1,0,0,1) l:SetStartPoint("TOPLEFT",10,10) l:SetEndPoint("BOTTOMRIGHT",10,10) f:Show