function changeTitle () {
	var subject = document.getElementById('mail_subject').value;
	
	if ((subject == null) || (subject == "")) {
		document.title = "SendMail";
		document.getElementById('message_title').innerHTML = "New Message";
	}
	else {
		document.title = "SendMail - " + subject;
		document.getElementById('message_title').innerHTML = subject;
	}
}

function showSignature () {
	document.getElementById('overlay_background').style.display = "block";
	document.getElementById('overlay_body').style.display = "block";
}

function hideSignature () {
	var signature = document.getElementById('signature_text').value;
	var message = document.getElementById('message_text').value;
	
	document.getElementById('message_text').value = message + "\n\n" + signature;
	
	document.getElementById('overlay_background').style.display = "none";
	document.getElementById('overlay_body').style.display = "none";
}

function messageSend () {
	document.getElementById('response_message_div').style.display = "block";
}
function changeTitle () {
	var subject = document.getElementById('mail_subject').value;
	
	if ((subject == null) || (subject == "")) {
		document.title = "SendMail";
		document.getElementById('message_title').innerHTML = "New Message";
	}
	else {
		document.title = "SendMail - " + subject;
		document.getElementById('message_title').innerHTML = subject;
	}
}

function showSignature () {
	document.getElementById('overlay_background').style.display = "block";
	document.getElementById('overlay_body').style.display = "block";
}

function hideSignature () {
	var signature = document.getElementById('signature_text').value;
	var message = document.getElementById('message_text').value;
	
	if (!((message == null) || (message == ""))) {
		document.getElementById('message_text').value = message + "\n\n" + signature;
	}
	
	document.getElementById('overlay_background').style.display = "none";
	document.getElementById('overlay_body').style.display = "none";
}

function messageSend () {
	document.getElementById('response_message_div').style.display = "block";
}
Check if signature is blank before adding to message
Check if signature is blank before adding to message

If the signature is blank, then nothing should be added to the message.
