Make/get LH open window texture?

[Nika Talaj]

I script, but I'm rather lame at making textures.  So I would like to install a texture-based set of window blinds in an addition I bought, and I happen to already have done the scripts for this quite a while ago.  Works using a wall switch, supports separate sets of blinds in different rooms, lalala.  I can find a closed blind texture, but the person who made the add-on did quite a nice job of matching the LH window glass (which just slightly dims the outside view), and I would like to do the same.

I looked on the marketplace, but this seems to be such an easy thing to do that I don't see it being sold. 

So do I just take a white texture and add alpha to it in Gimp?  That would be simple, but I suspect that it's actually more subtle than that, maybe subtly speckled as if it were diffused somehow ..... ummmm .... don't know how to do that.  Sooooo .... many ....... filters ....... in ....  GImp....

When I squint at the thumbnail of the texture on these windows, I seem to see faint lines under where mullion prims go.  Am I hallucinating?  What would the purpose of that be?  Shadows?

Edited November 14, 2019 by Nika Talaj