Issue:
Modal dialogs: Users must not be able to Tab away from a modal dialog without explicitly dismissing it
Why it matters:
The purpose of a modal dialog is to constrain user input (temporarily) to controls within the dialog. Just as mouse users should not be able to click elements outside the dialog, keyboard users should not be able to Tab to elements outside the dialog.
How to fix:
If a modal dialog contains a single focusable element (such as an 'OK' button), simply prevent any behaviour from occurring when the user presses the Tab key.
If a modal dialog contains multiple focusable elements, force focus to cycle through those elements until the dialog is dismissed by the user.
Steps to replicate:
Issue: Modal dialogs: Users must not be able to Tab away from a modal dialog without explicitly dismissing it
Why it matters: The purpose of a modal dialog is to constrain user input (temporarily) to controls within the dialog. Just as mouse users should not be able to click elements outside the dialog, keyboard users should not be able to Tab to elements outside the dialog.
How to fix:
W3 reference: https://www.w3.org/WAI/WCAG21/Understanding/focus-order.html