After combing through the forums, I've exhausted all the suggestions on how to save a CanvasSnapshot to disk in node-webkit. When in a browser, the image will download just as any normal file without a hitch--same if it's opened in a new window.
In node-webkit, whether windowed or full-screen, the download does not initiate. Also, showing the CanvasSnapshot in a new window doesn't enable any right-click 'Save As...' functionality. Saving the file to disk doesn't work, either, as node-webkit writes text to files.
In the game, there is a simple camera button that takes a canvas snapshot and should allow the player to save that file somehow. No issues in a browser but node-webkit is defying every attempt to save it.
If anyone knows of a way, or can find something to try, I'd greatly appreciate the help!