// Global object to hold drag information.
// Uses var browser and var iMinTop from openbrwnd.js

var dragObj = new Object();
var popOverlay;
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;
  }
	
  popOverlay = document.getElementById("PopWinOverlay");
  popOverlay.style.display = "block";
  popOverlay.style.top = "23px";
  popOverlay.style.height = (dragObj.elNode.clientHeight - 23) + "px";
  popOverlay.style.width = dragObj.elNode.clientWidth + "px";
  
  // 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(dragEvent) {

  var x, y;

  dragEvent = (dragEvent == null ? window.event : dragEvent);
  
  // Get cursor position with respect to the page.
  if (browser.isIE) {
    x = dragEvent.clientX + document.documentElement.scrollLeft + document.body.scrollLeft;
    y = dragEvent.clientY + document.documentElement.scrollTop + document.body.scrollTop;
  }
  if (browser.isNS) {
    x = dragEvent.clientX + window.scrollX;
    y = dragEvent.clientY + window.scrollY;
  }

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

  var newTopValue = (dragObj.elStartTop  + y - dragObj.cursorStartY);
  
  if (browser.isIE) {
	  if ( newTopValue < iMinTop )
	  {
			popOverlay.style.top = newTopValue - iMinTop;
			popOverlay.style.height = (dragObj.elNode.clientHeight - (newTopValue - iMinTop) ) + "px";
			newTopValue = iMinTop;
	  }
	  else
	  {
			popOverlay.style.top = "23px";
			popOverlay.style.height = (dragObj.elNode.clientHeight - 23) + "px";
	  }
  }
  else
  {
	  if ( newTopValue < iMinTop )
	  {
		  newTopValue = iMinTop;
	  }
  }
  dragObj.elNode.style.left = (dragObj.elStartLeft + x - dragObj.cursorStartX) + "px";
  dragObj.elNode.style.top = newTopValue + "px";

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

function dragStop(event) {

  // Stop capturing mousemove and mouseup events.

  var popOverlay = document.getElementById("PopWinOverlay");
  popOverlay.style.display = "none";

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