Looking through the code, I already found the problem, I think:
In the file plugin.php, function simple_ajax_auth_register_link() is missing a closing <a/> tag; it should be (line 160 etc.):
function simple_ajax_auth_register_link( $before = '', $after = '' ) {
$setup = get_option('simpleajaxauth');
return ( ! is_user_logged_in() && get_option( 'users_can_register' )) ? ( $before . '<a id="show_register">' . ( isEmpty($setup['register_text']) ? 'Register' : $setup['login_text'] ) . '<a/>' . $after ) : '';
}
Untested, but I think the missing end tag is preventing jQuery from recognizing the link.
That was not a complete solution… The link inside the login form has id pop_signup, while the link on the widget has id show_register. The jQuery looks for respectively (#pop_login, #pop_signup) and (#show_login, #show_signup).
So, if we change the id in the function that generates the link to show_signup, it starts working:
function simple_ajax_auth_register_link( $before = '', $after = '' ) {
$setup = get_option('simpleajaxauth');
return ( ! is_user_logged_in() && get_option( 'users_can_register' )) ? ( $before . '<a id="show_signup">' . ( isEmpty($setup['register_text']) ? 'Register' : $setup['login_text'] ) . '<a/>' . $after ) : '';
}
That’s more consistent, too.
You can mark this as resolved. 🙂