user_can_access_admin_page()

function user_can_access_admin_page() {
	global $pagenow, $menu, $submenu, $_wp_menu_nopriv, $_wp_submenu_nopriv,
		$plugin_page, $_registered_pages;

	$parent = get_admin_page_parent();

	if ( !isset( $plugin_page ) && isset( $_wp_submenu_nopriv[$parent][$pagenow] ) )
		return false;

	if ( isset( $plugin_page ) ) {
		if ( isset( $_wp_submenu_nopriv[$parent][$plugin_page] ) )
			return false;

		$hookname = get_plugin_page_hookname($plugin_page, $parent);

		if ( !isset($_registered_pages[$hookname]) )
			return false;
	}

	if ( empty( $parent) ) {
		if ( isset( $_wp_menu_nopriv[$pagenow] ) )
			return false;
		if ( isset( $_wp_submenu_nopriv[$pagenow][$pagenow] ) )
			return false;
		if ( isset( $plugin_page ) && isset( $_wp_submenu_nopriv[$pagenow][$plugin_page] ) )
			return false;
		if ( isset( $plugin_page ) && isset( $_wp_menu_nopriv[$plugin_page] ) )
			return false;
		foreach (array_keys( $_wp_submenu_nopriv ) as $key ) {
			if ( isset( $_wp_submenu_nopriv[$key][$pagenow] ) )
				return false;
			if ( isset( $plugin_page ) && isset( $_wp_submenu_nopriv[$key][$plugin_page] ) )
			return false;
		}
		return true;
	}

	if ( isset( $plugin_page ) && ( $plugin_page == $parent ) && isset( $_wp_menu_nopriv[$plugin_page] ) )
		return false;

	if ( isset( $submenu[$parent] ) ) {
		foreach ( $submenu[$parent] as $submenu_array ) {
			if ( isset( $plugin_page ) && ( $submenu_array[2] == $plugin_page ) ) {
				if ( current_user_can( $submenu_array[1] ))
					return true;
				else
					return false;
			} elseif ( $submenu_array[2] == $pagenow ) {
				if ( current_user_can( $submenu_array[1] ))
					return true;
				else
					return false;
			}
		}
	}

	foreach ( $menu as $menu_array ) {
		if ( $menu_array[2] == $parent) {
			if ( current_user_can( $menu_array[1] ))
				return true;
			else
				return false;
		}
	}

	return true;
}