//*****************************************************************************
// Do not remove this notice.
//
// Copyright 2001 by Mike Hall.
// See http://www.brainjar.com for terms of use.
//*****************************************************************************
// Determine browser and version.
function Browser() {

  var ua, s, i;

  this.isIE    = false;
  this.isNS    = false;
  this.version = null;

  ua = navigator.userAgent;

  s = "MSIE";
  if ((i = ua.indexOf(s)) >= 0) {
    this.isIE = true;
    this.version = parseFloat(ua.substr(i + s.length));
    return;
  }

  s = "Netscape6/";
  if ((i = ua.indexOf(s)) >= 0) {
    this.isNS = true;
    this.version = parseFloat(ua.substr(i + s.length));
    return;
  }

  // Treat any other "Gecko" browser as NS 6.1.

  s = "Gecko";
  if ((i = ua.indexOf(s)) >= 0) {
    this.isNS = true;
    this.version = 6.1;
    return;
  }
}

var browser = new Browser();

// Global object to hold drag information.

var dragObj = new Object();
dragObj.zIndex = 0;

function dragStart(event, id) {

  var el;
  var x, y;

  // If an element id was given, find it. Otherwise use the element being
  // clicked on.

  if (id)
    dragObj.elNode = document.getElementById(id);
  else {
    if (browser.isIE)
      dragObj.elNode = window.event.srcElement;
    if (browser.isNS)
      dragObj.elNode = event.target;

    // If this is a text node, use its parent element.

    if (dragObj.elNode.nodeType == 3)
      dragObj.elNode = dragObj.elNode.parentNode;
  }

  // Get cursor position with respect to the page.

  if (browser.isIE) {
    x = window.event.clientX + document.documentElement.scrollLeft
      + document.body.scrollLeft;
    y = window.event.clientY + document.documentElement.scrollTop
      + document.body.scrollTop;
  }
  if (browser.isNS) {
    x = event.clientX + window.scrollX;
    y = event.clientY + window.scrollY;
  }

  // Save starting positions of cursor and element.

  dragObj.cursorStartX = x;
  dragObj.cursorStartY = y;
  dragObj.elStartLeft  = parseInt(dragObj.elNode.style.left, 10);
  dragObj.elStartTop   = parseInt(dragObj.elNode.style.top,  10);

  if (isNaN(dragObj.elStartLeft)) dragObj.elStartLeft = 0;
  if (isNaN(dragObj.elStartTop))  dragObj.elStartTop  = 0;

  // Update element's z-index.

  dragObj.elNode.style.zIndex = ++dragObj.zIndex;

  // Capture mousemove and mouseup events on the page.

  if (browser.isIE) {
    document.attachEvent("onmousemove", dragGo);
    document.attachEvent("onmouseup",   dragStop);
    window.event.cancelBubble = true;
    window.event.returnValue = false;
  }
  if (browser.isNS) {
    document.addEventListener("mousemove", dragGo,   true);
    document.addEventListener("mouseup",   dragStop, true);
    event.preventDefault();
  }
}

function dragGo(event) {

  var x, y;

  // Get cursor position with respect to the page.

  if (browser.isIE) {
    x = window.event.clientX + document.documentElement.scrollLeft
      + document.body.scrollLeft;
    y = window.event.clientY + document.documentElement.scrollTop
      + document.body.scrollTop;
  }
  if (browser.isNS) {
    x = event.clientX + window.scrollX;
    y = event.clientY + window.scrollY;
  }

  // Move drag element by the same amount the cursor has moved.

  dragObj.elNode.style.left = (dragObj.elStartLeft + x - dragObj.cursorStartX) + "px";
  dragObj.elNode.style.top  = (dragObj.elStartTop  + y - dragObj.cursorStartY) + "px";

  hideShowCovered(dragObj.elNode);

  if (browser.isIE) {
    window.event.cancelBubble = true;
    window.event.returnValue = false;
  }
  if (browser.isNS)
    event.preventDefault();
}

function dragStop(event) {

  // Stop capturing mousemove and mouseup events.

  if (browser.isIE) {
    document.detachEvent("onmousemove", dragGo);
    document.detachEvent("onmouseup",   dragStop);
  }
  if (browser.isNS) {
    document.removeEventListener("mousemove", dragGo,   true);
    document.removeEventListener("mouseup",   dragStop, true);
  }
}

function getAbsolutePos(el) {
	var SL = 0, ST = 0;
	var is_div = /^div$/i.test(el.tagName);
	if (is_div && el.scrollLeft)
		SL = el.scrollLeft;
	if (is_div && el.scrollTop)
		ST = el.scrollTop;
	var r = { x: el.offsetLeft - SL, y: el.offsetTop - ST };
	if (el.offsetParent) {
		var tmp = getAbsolutePos(el.offsetParent);
		r.x += tmp.x;
		r.y += tmp.y;
	}
	return r;
}

function hideShowCovered(el)
{

	if (!browser.isIE)
	{
		return;
	}
	
	var tags = new Array("applet", "iframe", "select");
	var p = getAbsolutePos(el);
	var EX1 = p.x;
	var EX2 = el.offsetWidth + EX1;
	var EY1 = p.y;
	var EY2 = el.offsetHeight + EY1;

	for (var k = tags.length; k > 0; ) {
		var ar = document.getElementsByTagName(tags[--k]);
		var cc = null;

		for (var i = ar.length; i > 0;) {
			cc = ar[--i];

			p = getAbsolutePos(cc);
			var CX1 = p.x;
			var CX2 = cc.offsetWidth + CX1;
			var CY1 = p.y;
			var CY2 = cc.offsetHeight + CY1;

			if ((CX1 > EX2) || (CX2 < EX1) || (CY1 > EY2) || (CY2 < EY1)) {
				cc.style.visibility = "visible";
			} else {
				cc.style.visibility = "hidden";
			}
		}
	}
}

// show all elements that might be covered
function showMaybeCovered()
{
	if (!browser.isIE)
	{
		return;
	}
	
	var tags = new Array("applet", "iframe", "select");
	for (var k = tags.length; k > 0; ) {
		var ar = document.getElementsByTagName(tags[--k]);
		var cc = null;
		for (var i = ar.length; i > 0;) {
			cc = ar[--i];
			cc.style.visibility = "visible";
		}
	}
}