[Widget] How i get an unique ID?

Hello.

How i get an unique Wiget-ID?

I have write a Widget-Class and i use get_options/update_options to store the Widget-Settings in the database.

When ive send a POST-Request (Save the Widget) then he shows me a variety of information. About the instance itself, but I can not find out current information of the widgets. Funny.

Can someone help me?

class widget_categorys extends WP_Widget {
	[...]
	/* Backend */
	function form($instance) {
		print "<pre>";
		print_r($_POST);
		print_r($instance);