//get browser
var browser=navigator.appName;
var b_version=navigator.appVersion;
var version=parseFloat(b_version);
var isie = ((browser == 'Microsoft Internet Explorer') || (browser.match('msie')) ? true : false);

//set up ajax connection (called http_request) with server
var http_request;
function ajaxConnect() {
  http_request = false;
  // branch for native XMLHttpRequest object: Mozilla, etc
  if(window.XMLHttpRequest) {
    try {
      http_request = new XMLHttpRequest();
    } catch(e) {
      http_request = false;
    }
  // branch for IE/Windows ActiveX version: IE 6+
  } else if(window.ActiveXObject) {
    try {
    http_request = new ActiveXObject("Msxml2.XMLHTTP");
    // branch for IE/Windows ActiveX version: IE other
    } catch(e) {
      try {
        http_request = new ActiveXObject("Microsoft.XMLHTTP");
      } catch(e) {
        http_request = false;
      }
    }
  }
}

function set_dims() {
	ajaxConnect();
	var url = 'settings_save.php?screen_width=' + screen.width + '&screen_height=' + screen.height;
	http_request.open('GET', url, true);
	//do nothing
	http_request.send(null);
}

function init_script() {
	//getselsub: which sub_region has been selected
	ajaxConnect();
	var url = 'get_selsub.php';
	//copied from http://en.wikipedia.org/wiki/XMLHttpRequest
	var request =  new XMLHttpRequest();
	request.open("GET", url, false);
	request.send(null);
	if(!request.getResponseHeader("Date")) {
		var cached = request;
		request =  new XMLHttpRequest();
		var ifModifiedSince = cached.getResponseHeader("Last-Modified");
		ifModifiedSince = (ifModifiedSince) ?
				ifModifiedSince : new Date(0); // January 1, 1970
		request.open("GET", url, false);
		request.setRequestHeader("If-Modified-Since", ifModifiedSince);
		request.send("");
		if(request.status == 304) {
			request = cached;
		}
	}
	selsub = request.responseText;
}