Wordpress Functions (background image, Appearance/Menus, dashboard link for tutorial videos, ifMobile function)

wp_functions.php

<?php
// functions.php file

// anchor all forms on site on submission (Gravity Forms)
add_filter( 'gform_confirmation_anchor', '__return_true' );

//if mobile function
function isMobile() {
    return preg_match("/(android|avantgo|blackberry|bolt|boost|cricket|docomo|fone|hiptop|mini|mobi|palm|phone|pie|tablet|up\.browser|up\.link|webos|wos)/i", $_SERVER["HTTP_USER_AGENT"]);
}

if ( function_exists( 'add_theme_support' ) ) {
    add_theme_support( 'post-thumbnails' );
    set_post_thumbnail_size( 150, 150, true ); // default Post Thumbnail dimensions (cropped)

    // additional image sizes
    add_image_size( 'news-index-thumbnail', 345, 400 ); //345 pixels wide
}

// add Menu
function mytheme_register_nav_menus() {
    register_nav_menus(
        array(
            'primary_navigation' => 'Primary Navigation',
            'footer_navigation' => 'Footer Navigation'
        )
    );
}
add_action( 'after_setup_theme', 'mytheme_register_nav_menus' );

// background and header image
function mytheme_setup() {
    add_custom_background();
    add_custom_image_header();
}
add_action( 'after_setup_theme', 'mytheme_setup' );

// DASHBOARD
/**
 * Add a widget to the dashboard.
 *
 * This function is hooked into the 'wp_dashboard_setup' action below.
 */
function example_add_dashboard_widgets() {

	wp_add_dashboard_widget(
                 'tutorial_dashboard_widget',         // Widget slug.
                 'Tutorial Videos',         // Title.
                 'tutorial_dashboard_widget_function' // Display function.
        );
}
add_action( 'wp_dashboard_setup', 'example_add_dashboard_widgets' );

/**
 * Create the function to output the contents of our Dashboard Widget.
 */
function tutorial_dashboard_widget_function() {

	// Display whatever it is you want to show.
	echo "<h1>Hello, CLIENT NAME!</h1><br><br>";
    echo '<p>The tutorial videos can be seen <a href="/tuts/" target="_blank"><strong>here</strong></a>.</p>';
}