function invert_select()
{
	for(var i=0;i<document.edit_form.length;++i) 
	{
		if (document.forms[0].elements[i].type == "checkbox")
		{
			if (document.forms[0].elements[i].checked == true)
			{
				document.forms[0].elements[i].checked = false;
			}
			else 
			{
				document.forms[0].elements[i].checked = true;
			}
		}
	}
}


function select_all()
{
	for(var i=0;i<document.edit_form.length;++i) 
	{
		if (document.forms[0].elements[i].type == "checkbox")
		{
			document.forms[0].elements[i].checked = true;
		}
	}
}

function deselect_all()
{
	for(var i=0;i<document.edit_form.length;++i) 
	{
		if (document.forms[0].elements[i].type == "checkbox")
		{
			document.forms[0].elements[i].checked = false;
		}
	}
}