You create a canvas app. A user is not able to determine which field currently has focus. You run App checker to identify errors. You need to verify that the focused border thickness is set to a…

The Rules section typically reports on formula errors, delegation warnings, and other logical or syntax-related issues, not direct accessibility problems like focus visibility.

The Performance section suggests ways to optimize the app's speed and efficiency, which is unrelated to the visibility of the focus indicator.

The Accessibility section of the App Checker is dedicated to identifying issues that might prevent users, particularly those with disabilities, from effectively interacting with the app. Problems like an invisible focus border directly impact accessibility, making it difficult for keyboard users to navigate, and are therefore reported under this category.

Runtime issues generally refer to errors that occur during the app's execution, such as data connection failures, rather than design-time accessibility considerations.