function hide_select(){
	var select = document.getElementById('selectproduct');
	
	if(select.style.visibility == "hidden")
	{
	select.style.visibility="visible"
	}else{
	select.style.visibility="hidden";
	}
} 


function hide_all(){
	var select = document.getElementsByTagName("select");
	for (var i = 0; i < select.length; i++) { 
	
		if(select[i].style.visibility == "hidden")
		{
		select[i].style.visibility="visible"
		}else{
		select[i].style.visibility="hidden";
		}

    }
}