Sorry about that. I was more making the point that it's not a cygwin
port of emac's fault.
I also have this problem using emacs built locally from the original
gnu emacs source code. And also from the cygwin port.
C-z puts emacs off the screen, but when its re-displayed the focus
doesn't come back into the editting buffer. I have to first click on
any ol option on the top menu, and it re-activiates something that
enable editting back in the buffer.
environment: putty (also built from original source code)
This problem / hanging does not occur when emacs has been moved off
the screen by clicking on the [-] tab in the upper right side of the
emacs frame.
Can you duplicate this on your system?
C-Z # then [SHIFT][TAB] back to emacs to get it back up on the
screen. It should be frozen then. Workaround, click on [File] or
something and then escape from it and you can work in the normal
buffer.