//functions.js
	
	function runajax(objID, serverPage) {
	
		//Create a boolean variable to check for a valid Internet Explorer instance.
		var xmlhttp = false;
		
		//Check if we are using IE.
		try {
			//If the javascript version is greater than 5.
			xmlhttp = new ActiveXObject("Msxml2.XMLHTTP");
		} catch (e) {
			//If not, then use the older active x object.
			try {
				//If we are using Internet Explorer.
				xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
			} catch (E) {
				//Else we must be using a non-IE browser.
				xmlhttp = false;
			}
		}
		//If we are using a non-IE browser, create a javascript instance of the object.
		if (!xmlhttp && typeof XMLHttpRequest != 'undefined') {
			xmlhttp = new XMLHttpRequest();
		}
		
		var obj = document.getElementById(objID);
		xmlhttp.open("GET", serverPage);
		
		xmlhttp.onreadystatechange = function() {
			if (xmlhttp.readyState == 4 && xmlhttp.status == 200) {
				obj.innerHTML = xmlhttp.responseText;
			}
		}		
		xmlhttp.send(null);		
	}
	
	// Function to handle an image click
	// The click passes the current category plus the name of the clicked image
	// and it's position in the image array (arrayref)
	// arrayref is used by midpic.php to reference the current caption and description
	function imageclick (cat, img, arrayref) {
		showload();
		runajax ("middiv", "midpic.php?category=" + cat + "&curimage=" + img + "&arrayref=" + arrayref);
		runajax ("picstrip", "picstrip.php?category=" + cat + "&curimage=" + img);
	}
	
	//Function to handle the category navigation
	function tabclick (cat) {
		showload();
		runajax ("middiv", "midpic.php?category=" + cat);
		runajax ("picstrip", "picstrip.php?category=" + cat);
		runajax ("gallerynav", "gallerynav.php?category=" + cat);
		document.getElementById("caption").innerHTML = '<h3>&nbsp;</h3>';
	}
	
	//Function to clear error messages.
	function clearmes (){
		//Clear any old error messages.
		document.getElementById("messagediv").innerHTML = "";
	}
	
	//Function to show a loading message.
	function showload (){
		document.getElementById("middiv").innerHTML = "<div class=\"loading\">Loading...</div>";
	}
	
	
	// Functions to change caption text
	// Caption appears above picture strip when rolling over the thumbs
	function setCaption(caption)
	{
		document.getElementById("caption").innerHTML = caption;
	}
	function hideCaption()
	{
		document.getElementById("caption").innerHTML = "<h3>&nbsp;</h3>";
	}