Devtool, toolbar and other features was removed from nw 0.13.*.
How can I to use the devtool in current versions?
I created a nw project who uses nw 0.12.1. I decided to upgrade it to current version, and then, the desired tools was absents.
There are docs about devtools in nw
open DevTools programmatically using NW.js API win.showDevTools()
Or...
Remote Debugging
You can use the --remote-debugging-port=port command line option to specify which port the DevTools should listen to. For example, by running nw --remote-debugging-port=9222, you can open http://localhost:9222/ in your browser to visit the debugger remotely.