<?php

if (function_exists( 'add_theme_support' )){
    add_filter('manage_posts_columns', 'posts_columns', 5);                     // All posts column list
    add_action('manage_posts_custom_column', 'posts_custom_columns', 5, 2);     // Cloumn content
    add_filter('manage_pages_columns', 'posts_columns', 5);                     // All pages column list
    add_action('manage_pages_custom_column', 'posts_custom_columns', 5, 2);     // Cloumn content
    add_filter('manage_projects_posts_columns', 'posts_columns', 1);            // Only custom post 'project' column list
    add_action('manage_projects_posts_custom_column', 'posts_custom_columns', 1, 2);  // Column content
}
function posts_columns($defaults){
    $defaults['tmx_post_thumbs'] = __('Thumbs');  // Column title, you can add more columns in $defaults array
    return $defaults;
}
function posts_custom_columns($column_name, $id){
    if($column_name === 'tmx_post_thumbs'){       // print column content
        if ( !has_post_thumbnail() ) {            // Default thumbnail
            echo '<img height="80" width="80" src="'.trailingslashit( get_stylesheet_directory_uri() ) . 'resources/img/pr-03.jpg" />';
        }
        else {
            echo the_post_thumbnail( array(125,80) );
        }
    }
}