Add a NextPage button on WorldPress Editor

Open the functions.php in your theme directory. For example, if your theme is tigra, then open the functions.php in <wordpress-path>/wp-content/themes/tiga.[…]

Add the following lines at the bottom of functions.php, after the last close bracket (?>)

<?php
add_filter(‘mce_buttons’, ‘add_nextpage’);

function add_nextpage($buttons) {
if (!in_array(‘wp_page’, $buttons)) {
if (!in_array(‘wp_more’, $buttons)) {
$last = array_pop($buttons);
$buttons[] = “wp_page”;
$buttons[] = $last;
}else{
$txt = implode(‘|’, $buttons);
$txt = str_replace(‘wp_more|’,’wp_more|wp_page|’, $txt);
$buttons = explode(‘|’, $txt);
}
}
return $buttons;
}
?>

Refresh the browser. You should see the new button being added.