我制作了一个自定义插件POLL . 当我激活它时，默认图标会出现在侧边栏上。我想更改此默认图标。这是我写的代码init.php 文件

add_action(\'admin_menu\', \'mt_add_pages\');



// action function for above hook
function mt_add_pages() {

    // Add a new top-level menu (ill-advised):
    add_menu_page(__(\'Poll\',\'menu-test\'), __(\'Poll\',\'menu-test\'), \'manage_options\', \'manage-polls\', \'poll_page\' );

    // Add a submenu to the custom top-level menu:
    add_submenu_page(\'manage-polls\', __(\'Add New Poll\',\'menu-test\'), __(\'Add New Poll\',\'menu-test\'), \'manage_options\', \'add-poll\', \'add_new_poll_page\');


}



// mt_toplevel_page() displays the page content for the custom Test Toplevel menu
function poll_page() {
    if (!current_user_can(\'manage_options\'))
    {
      wp_die( __(\'You do not have sufficient permissions to access this page.\') );
    }
    echo "<br/>";
    echo "<div>";
    echo \'<div style="float:left;"><img width="20" height = "20" src="\'.site_url().\'/wp-content/plugins/poll/images/poll_red.png" /></div>\';
    echo "</div>";
    echo "<h2>" . __( \'Manage Polls\', \'menu-test\' ) . "</h2>";

    include_once \'manage-polls.php\';
}

// mt_sublevel_page() displays the page content for the first submenu
// of the custom Test Toplevel menu
function add_new_poll_page() {
    if (!current_user_can(\'manage_options\'))
    {
      wp_die( __(\'You do not have sufficient permissions to access this page.\') );
    }
    echo "<br/>";
    echo "<div>";
    echo \'<div style="float:left;"><img width="20" height = "20" src="\'.site_url().\'/wp-content/plugins/poll/images/poll_red.png" /></div>\';
    echo "</div>";
    include_once \'poll_form.php\';
}