window-revert documentation

[lynch@aristotle.ils.nwu.edu]

The window-revert documentation should mention that window-filename (as
well as window-needs-saving-p) needs to return a non-nil value for the
menu-item to be enabled.  I hadn't thought about it enough and had made my
own slot to hold the filename.  Only figured it out by disassembling
ccl::revert-window-update-function or whatever it is.

Again, thanks for making these menu-items simple to use.
"TANSTAAFL" Rich lynch@ils.nwu.edu