The textures are stored as indexes in the borders key of the parent frame. If you were to do
ZaxBorders=CreateFrame("frame") instead of
local f=CreateFrame("frame"), you can change the colors like so:
Lua Code:
for i=1,4 do
ZaxBorders.borders[i]:SetColorTexture(r,g,b,a)
end
Also, the way the code is currently ordered, 1 is top, 2 is right, 3 is bottom, and 4 is left. You can change the color of, say, just the bottom with this:
ZaxBorders.borders[3]:SetColorTexture(r,g,b,a)