Hmm, I have 2.3.4 and it works fine for me. I'll make a package for it a little later and put here.
This package's addition is one of two important modifications that will be hitting the Pro version of NGUI in a short while. I am very hesitant about both, so I will most likely keep them Pro-only for a few weeks until I make sure that there are no adverse side-effects (the other feature is the potential fix for the Z vs depth distinction, in case you're curious).
+1
You would have to do it in the shader then.
You can add that in your own shader if you want it though.
No. 2.3.6 is out already. Those will be in a coming version