Default All Posts to the Current User’s Posts

When clicking on All Posts in the main menu, Administrators and Editors will normall see all posts. Use this to change the default view to the user’s own posts. See comments to limit the change to users of a certain roll.

add_action( 'admin_menu', 'show_users_posts_by_default' );
function show_users_posts_by_default() {

	/*if current user is an 'administrator' do nothing*/
	//if ( current_user_can( 'add_users' ) ) return;

	/*if current user is an 'administrator' or 'editor' do nothing*/
	//if ( current_user_can( 'edit_others_pages' ) ) return;

	global $submenu, $user_ID;
	$submenu['edit.php'][5][2] = 'edit.php?author='. $user_ID;
}

Hide Menu Items

If you need to hide menus from the sidebar of the administration area, you can use this. Keep in mind, this method does not block access, just hides the link.

add_action('admin_menu', 'hide_menu_links');
function hide_menu_links(){
  	global $menu,$submenu;

  	if ($submenu['plugins.php'][15][0] == 'Editor')
	unset($submenu['plugins.php'][15]);

  	if ($menu[15][0] == 'Links')
	unset($menu[15]);

}
// $menu
//     [2] => {Dashboard}
//     [4] => {separator}
//     [5] => {Posts}
//     [10] => {Media}
//     [15] => {Links}
//     [20] => {Pages}
//     [25] => {Comments}
//     [59] => {separator}
//     [60] => {Appearance
//     [65] => {Plugins}
//     [70] => {Users}
//     [75] => {Tools}
//     [80] => {Settings}
//     [99] => {separator}

// $submenu
//     [index.php] =>
//         [0] => {Dashboard}
//         [10] => {Updates}
//     
//     [edit.php] =>
//         [5] => {Posts}
//         [10] => {Add New}
//         [15] => {Categories}
//         [16] => {Post Tags}
//     
//     [upload.php] =>
//         [5] => {Library}
//         [10] => {Add New}
//     
//     [link-manager.php] =>
//         [5] => {Links}
//         [10] => {Add New}
//         [15] => {Link Categories}
//     
//     [edit.php?post_type=page] =>
//         [5] => {Pages}
//         [10] => {Add New}
//     
//     [themes.php] =>
//         [5] => {Themes}
//         [7] => {Widgets}
//         [10] => {Menus}
//     
//     [plugins.php] =>
//         [5] => {Plugins}
//         [10] => {Add New}
//         [15] => {Editor}
//     
//     [users.php] =>
//         [5] => {Users}
//         [10] => {Add New}
//         [15] => {Your Profile
//     
//     [tools.php] =>
//         [5] => {Tools}
//         [10] => {Import}
//         [15] => {Export}
//     
//     [options-general.php] =>
//         [10] => {General}
//         [15] => {Writing}
//         [20] => {Reading}
//         [25] => {Discussions}
//         [30] => {Media}
//         [35] => {Privacy}
//         [40] => {Permalinks}

Hide Plugin Update count

In case you need to hide the plugin update count (can’t/don’t want to update yet) you can hide it with this. Can be especially useful if you don’t want clients to wander over the the update area.

add_action('admin_menu', 'remove_plugin_update_count');
function remove_plugin_update_count(){
    global $menu, $submenu;
    $menu[65][0] = 'Plugins';
    $submenu['index.php'][10][0] = 'Updates';
}