[Bug] 1.3.18-1: Problem with arrow keys and rxvt/bash/mc

[Steve O]

Marcel Telka wrote:
> Up/down/left/right arrows produces sometimes upper letters (for example
> 'D' while pressing left) instead of a cursor moving. To reproduce try run mc
> and press the arrow keys in blue mc's window (for moving cursor through
> files or moving cursor left-right in command line).

I'm able to reproduce this without bash, and with xterm instead of rxvt.
That narrows the problem down to some changes I made to the cygwin 
tty code. 

The change I suspect is one that writes characters one at a time to the
slave, instead of a bulk write of the entire buffer.  Thus, it's 
possible for the slave to read half of an escape sequence in a 
race condition.  I was under the impression that the slave, mc in
this case, should be able to deal with this condition, or am I mistaken?

Thanks for pointing out this test case.
-steve