The QBanner component creates a banner element to display a prominent message and related optional actions.
According to the Material Design spec, the banner should be “displayed at the top of the screen, below a top app bar” - but of course you can put one anywhere that makes sense, even in a QDialog.
Usage
Accessibility v2.25+
QBanner renders with role="alert", an assertive live region: a banner inserted dynamically (say, an error appearing after a failed request) is announced immediately, while one rendered together with the page is not announced at all. For a persistent, informational banner that should not interrupt, override the role by passing an attribute — role="status" for polite announcements, or a landmark role such as region (with an aria-label) for purely static content.