[xfce4-terminal] Large delay in prompt echoing after completion of a command which runs inside a tmux session

[Daniel Fishman]

> 
> It would definitely help if you tested it on another machine. I wasn't able to reproduce the problem on the 64-bit one that I have here.
> 

The problem didn't reproduce on another 64-bit machine. I must note though
that the two original machines (both 32 and 64 ones) use the same distribution
and therefore have identical sets of installed components (with the bit-ness
difference, of course). The second 64-bit machine has a different and a much 
older distribution which has xfce 4.8 installed (instead of xfce 4.12). I did
compile the same version of tmux for the test, but the other components were
used as is. So again, the test is not as conclusive as possible.