var block_cur=1;
var is_previews=0;


function display_buttons() {
	div_c = document.getElementById("customers");		
	node_list = div_c.childNodes;	
	l=node_list.length-1;		
	but_l = document.getElementById("s_l");	
	but_r = document.getElementById("s_r");	
	if (is_previews) {
		but_l2 = document.getElementById("s_l2");	
		but_r2 = document.getElementById("s_r2");	
	}
	if (node_list[0].id=="c1") {
		but_l.className="h";
		if (is_previews) {
			but_l2.className="h";
		}
	} 
	else {
		but_l.className="v";
		if (is_previews) {
			but_l2.className="v";
		}
	}
	if (node_list[l].id=="c4") {
		but_r.className="h";
		if (is_previews) {
			but_r2.className="h";
		}
	}
	else {
		but_r.className="v";
		if (is_previews) {
			but_r2.className="v";
		}
	}
}

function go_back() {	
	div_c = document.getElementById("customers");		
	if (is_previews) {
		div_pr = document.getElementById("previews");
	}
	node_list = div_c.childNodes;	
	l=node_list.length-1;	
	for (i = l; i >= 0; i--) {
		r=i-block_cur+3;
		node_list[i].id="c"+r;
		node_list[i].innerHTML+="";			
		if (is_previews) {
			div_pr.getElementsByTagName("div")[i].id="pr"+r;
			div_pr.getElementsByTagName("div")[i].innerHTML+="";	
		}
	}	
	block_cur--;
	display_buttons();
}

function go_forward() {	
	div_c = document.getElementById("customers");
	if (is_previews) {
		div_pr = document.getElementById("previews");
	}
	node_list = div_c.childNodes;	
	l=node_list.length;
	for (i = 0; i < l; i++) {			
		r=i-block_cur+1;		
		node_list[i].id="c"+r;
		node_list[i].innerHTML+="";	
		if (is_previews) {
			div_pr.getElementsByTagName("div")[i].id="pr"+r;
			div_pr.getElementsByTagName("div")[i].innerHTML+="";	
		}
	}	
	block_cur++;
	display_buttons();
}


function set_column(n) {
	for (j = 0; j < n; j++) {	
		go_forward();			
	}
}