As far as I can tell, that might be an issue with the windowing system you use, it might not refresh the text control until it returns to the main control loop. I don't know much about gui programming, so I can't tell.

Also, it can be a problem wit buffering or that you are reading the output line-by-line with the diamond operator.

You shoud probably post it as a new SOPW, as this is a different question than the original one.