well, I just tried pasting that above link in my browser and I got
404 - Not found - File /Applications/Pinegrow.app/Contents/Resources/app.nw/help/examples/pinepoems/pinepoems.html can not be read by Pinegrow: Error: ENOENT: no such file or directory, open '/Applications/Pinegrow.app/Contents/Resources/app.nw/help/examples/pinepoems/pinepoems.html’
but if I open a page in file in PG then, hit CMD+B to open in browser, then that file will open just fine.
But… if I open the tutorials included with PG and fire up the PinePoems page, CMD+B
it opens fine! but the URL that this opens up with is (ignore the _5.93, I have different PG versions installed.)
so same port, (4000) but 127.0.0.1 instead of localhost
Check port and that difference above?
And have you tried different browsers, incase it is browser specific? (my examples above work in Safari, Chrome, Firefox)
I checked in case it was some sort of security certificate/plugin weirdness.
have you tried it with Mac Firewall disabled? (and not connected to internet, of course :))