Unagi Compositing Manager

I'm using awesome + shifty. Considering the two tags, on with 2 terms A and B, and another with one term C. I type something in B, to recognize it. If i move B to tag 2, it sometimes but not always bug: there is a placeholder for B where i can only see the background, and the sloppy focus works like if it was here, i can type things which are executed in the term, but even if i switch to another tag and come back i cannot see its content. If i then kill Unagi, the window appears in the placeholder and i can see what i typed earlier.

I was unable to see what triggers the bug, sorry.