On focus: moving focus to another control
Load page and tab into the Email address text input. Try clicking with mouse inside the email text input. You will not be able to as the focus always gets passed to the password field.
On focus: changing experience with a link
Load the page and tab to the link.
On focus: opening an alert (or new window) with a link
Tab to the link. A confirmation will open. A keyboard user will never be able to get to the "Can't reach me" button unless they answer Cancel in the dialog.