Activating edit mode through the Edit module shifts the user from a viewing experience to an interaction experience. The user interacts with the content no longer as a consumer, but as an editor. For this reason, the components that respond to tabbing navigation (pressing the tab key to jump from one interactable component to the next) must change to reflect an editing workflow rather than a content consumption workflow.
When a user activates edit mode, re-flow the page tabbing composition and order. The core overlay module has an example of this process in the
Propose a patch.
User interface changes
Keyboard users will note that upon entering edit mode, that tab index of the page's components will change. Only editable fields and toolbar controls will be accessible from the keyboard.