Wordpress: virtual editor

gistfile1.txt

<?php 
//Set the Visual Editor Width Relative to Your Themes Content Width  
add_action( 'after_setup_theme', 'wptuts_theme_setup' );
function wptuts_theme_setup() {
    set_user_setting( 'dfw_width', 1000 );//In this example the full width will be 1000 pixels.

}

add_action( 'after_setup_theme', 'wptuts_theme_setup' );
function wptuts_theme_setup() {
    // /wp-content/themes/theme-name/css/my-first-style.css
    add_editor_style( array( 'css/my-first-style.css', 'css/my-second-style.css' ) );
}