You can use a cross platform file system event notification package like fsnotify/fsnotify or rjeczalik/notify, both on github. Instead of HEAD, may be just watch .git/index and when it changes, do git ls-files and see what changed. This will also catch local git add etc. though this probably doesn't matter.

On Feb 16, 2017, at 5:05 AM, Paul Lalonde <paul.a.lalonde@gmail.com> wrote:

I'll give Watch and a bit of scripting a shot.  I couldn't find a git "HEAD changed" hook to tie to, so Watch is pretty much the right thing.

Thanks!

On Wed, Feb 15, 2017 at 9:04 PM Erik Quanstrom <quanstro@quanstro.net> wrote:
try writing the file?  ðŸ˜€

On Feb 15, 2017 5:05 AM, Paul Lalonde <paul.a.lalonde@gmail.com> wrote:
I know I'm not the only acme user who uses Git extensively :-)
Is there some way to tell if a file is changed on disk that is open in an editor window?  I frequently change branches and I often find myself editing stale versions.  I notice when comes time to Put, but that's a bit late.

Any tips to share? 

Paul