function setWriterOnChange(select_o)
{
	document.getElementById('writer_1').style.display = 'none';
	document.getElementById('writer_2').style.display = 'none';
	document.getElementById('writer_3').style.display = 'none';
	

	var value_u = select_o.options[select_o.selectedIndex].value;

	if (value_u == '1')
	{
		document.getElementById('main_spacer').style.display = '';
		document.getElementById('host_1').style.display = '';	
		document.getElementById('writer_1_spacer').style.display = '';
		document.getElementById('writer_1').style.display = '';
	}

	if (value_u == '2')
	{
		document.getElementById('main_spacer').style.display = '';
		document.getElementById('host_1').style.display = '';
		document.getElementById('host_2').style.display = '';	
		document.getElementById('writer_1_spacer').style.display = '';
		document.getElementById('writer_2_spacer').style.display = '';
		document.getElementById('writer_1').style.display = '';
		document.getElementById('writer_2').style.display = '';
	}
	if (value_u == '3')
	{
		document.getElementById('main_spacer').style.display = '';
		document.getElementById('host_1').style.display = '';
		document.getElementById('host_2').style.display = '';
		document.getElementById('host_3').style.display = '';
		document.getElementById('writer_1_spacer').style.display = '';
		document.getElementById('writer_2_spacer').style.display = '';
		document.getElementById('writer_3_spacer').style.display = '';
		document.getElementById('writer_1').style.display = '';
		document.getElementById('writer_2').style.display = '';
		document.getElementById('writer_3').style.display = '';
	}
	
}


var setDisplaySwitch = function(element_s)
{
	if (element_s)
	{
		var element_o = document.getElementById(element_s);

		if (element_o)
			element_o.style.display = element_o.style.display ? '' : 'none';
	}
};


var TestFileType = function(fileName, fileTypes) 
{
	if (!fileName) return;
	dots = fileName.split(".");
	//get the part AFTER the LAST period.
	fileType = "." + dots[dots.length-1];
	return (fileTypes.join(".").indexOf(fileType) != -1) ? alert('That file is OK!') : alert("U kunt alleen bestanden versturen van het type:  \n\n" + (fileTypes.join(" .")) + "\n\nSelecteer een ander type en probeer het opnieuw");
}