I tried zsh on cygwin and I found the behavior to be odd when resizing the terminal window (using a number of different terminal interfaces, rxvt, putty, etc). The screen wouldn't redraw as one might expect. Is this common to all zsh or is it just a cygwin issue?
linux: http://stuff.mit.edu/~jdong/misc/zshrc os x: http://stuff.mit.edu/~jdong/misc/zshrc-osx-blackonwhite