NW.js packaged app accessibility tree exposure and screen reader configuration

A packaged NW.js application relies on the bundled Chromium accessibility tree to expose DOM roles, labels and states to native assistive technologies. The user-facing workflow needs predictable screen reader compatibility across platforms, but there is no documented NW.js configuration that explicitly controls or tests that mapping.

Accessibility support is determined by the Chromium version and host OS rather than NW.js-specific APIs, and the relationship between package manifest window settings and accessibility tree exposure is not clearly defined. The permission boundary between renderer content and native accessibility is also unspecified, and behavior is version-sensitive.

What documented manifest or runtime option exists to enforce consistent accessibility tree exposure for packaged windows? How is accessibility tree mapping expected to behave for windows created via window.open relative to the main window? Is there a supported method to verify screen reader compatibility within the NW.js user-facing workflow?