Ashley - NWJSexport and preview is broken in 263beta version
262 and 263 version. 263 - small image
Develop games in your browser. Powerful, performant & highly capable.
Are you using "Request fullscreen (centered)"? This bug was fixed:
Browser: Request fullscreen 'Centered' incorrectly did 'Letterbox scale'
Change it to request fullscreen letterbox scale and it'll work the same again.
Thank you for ansfer.