function showInCenter(id) {
   var winCenterX;
   var winCenterY;
   if (window.innerWidth) { //if browser supports window.innerWidth
       winCenterX = window.innerWidth/2;
       winCenterY  = window.innerHeight/2;
   } else if (document.all) { //else if browser supports document.all (IE 4+)
       winCenterX = document.body.clientWidth/2;
       winCenterY = document.body.clientHeight/2;
   }
   var obj = $(id);
   var objHeight = obj.style.height;
   var objWidth  = obj.style.width;
   //alert(objHeight+"  "+objWidth);
   obj.style.top = (winCenterY-100) + 'px';
   obj.style.left = (winCenterX-(objWidth/2)-100) + 'px';
   setDisplay(id,'block');
}

function changeBgColor(obj, color) {
  obj.style.backgroundColor = color;
}
function findPos(obj) {
  var curleft = curtop = 0;
  do {
	 curleft += obj.offsetLeft;
	   curtop += obj.offsetTop;
  } while (obj = obj.offsetParent);
  return [curleft,curtop];
}
function findPosById(objId) {
  return findPos($(objId));
}
function showSubCat(obj, id) {
  var leftOffSet = 155;
  var dimension = findPos(obj);
  var menu = $(id);
  menu.style.top = (dimension[1]-2) + 'px';
  menu.style.left = (dimension[0] + leftOffSet) + 'px';
  setDisplay(id,'block');
  showCatContent(id);
  changeBgColor(obj, '#E9EAE7');
  //obj.style.borderTopColor = '#000000';
  //obj.style.borderTopWidth = 2;
}
function toggleItemBlock(oid){
    var imageState = imgSwap(oid);
	//alert(imageState);
	if (imageState.endsWith("expand.gif")) {
        //var now = new Date();
		//alert("call");
        //var myAjax = new Ajax.Updater(oid, '/include/cat'+oid+'.html', { method: 'get' });
		showCatContent(oid);
    }
    toggleDisplay(oid);         
}
function validate(searchForm) {
  //var keywords = $('keywords');
  var keywords = searchForm.keywords;
  var sitesearch = $('sitesearch');
  var selectedIndex = sitesearch.selectedIndex;
  var target = sitesearch.options[selectedIndex].text;
  //alert (target);
  //alert ("["+keywords.value+"]");
  if (keywords.value == "" || keywords.value == " " || keywords.value == "  " || keywords.value == "   ") {
      if (target == "Book") {
          alert("Please enter a search pattern in the title or author names of the books. \n\nYou may use Regular Expression to build patterns");
	  } else {
	      alert("Please enter search keywords or pattern");
	  }
      keywords.focus();
      return false;
  } 
  //var searchForm = $('searchForm');
  if (target == "Book") {
	  //showInCenter('processing');
	  setDisplay('processing','block');
      searchForm.action = "http://freecomputerbooks.com/cgi-bin/searchBooks";
	  searchForm.method = "post";
	  searchForm.target = "_self";  
  } else {
      searchForm.action = "http://www.google.com/custom";
	  searchForm.method = "get";
	  searchForm.target = "_blank";
	  searchForm.q.value = keywords.value;
  }
  return true;
}
function displayGoole() {
  var sitesearch = $('sitesearch');
  var selectedIndex = sitesearch.selectedIndex;
  var target = sitesearch.options[selectedIndex].text;
  if (target == "Book") {
      setDisplay('google','none');
  } else {
      setDisplay('google','inline');
  }
}

function ietruebody(){
return (document.compatMode && document.compatMode!="BackCompat")? document.documentElement : document.body
}

function ddrivetip(thetext, thecolor, thewidth){
  if (ns6||ie){
      if (typeof thewidth!="undefined") tipobj.style.width=thewidth+"px";
      if (typeof thecolor!="undefined" && thecolor!="") 
		  tipobj.style.backgroundColor=thecolor;
      tipobj.innerHTML=thetext;
      enabletip=true;
      return false
  }
}

function positiontip(e){
  if (enabletip){
      var curX=(ns6)?e.pageX : event.clientX+ietruebody().scrollLeft;
      var curY=(ns6)?e.pageY : event.clientY+ietruebody().scrollTop;
	  //alert(curX+"   "+curY);
      //Find out how close the mouse is to the corner of the window
      var rightedge=ie&&!window.opera? ietruebody().clientWidth-event.clientX-offsetxpoint : window.innerWidth-e.clientX-offsetxpoint-20
      var bottomedge=ie&&!window.opera? ietruebody().clientHeight-event.clientY-offsetypoint : window.innerHeight-e.clientY-offsetypoint-20

      var leftedge=(offsetxpoint<0)? offsetxpoint*(-1) : -1000

       //if the horizontal distance isn't enough to accomodate the width of the context menu
      if (rightedge<tipobj.offsetWidth)
          //move the horizontal position of the menu to the left by it's width
          tipobj.style.left=ie? ietruebody().scrollLeft+event.clientX-tipobj.offsetWidth+"px" : window.pageXOffset+e.clientX-tipobj.offsetWidth+"px";
      else if (curX<leftedge)
          tipobj.style.left="5px";
      else
          //position the horizontal position of the menu where the mouse is positioned
          tipobj.style.left=curX+offsetxpoint+"px";

      //tipobj.style.left="333px";
     // alert(tipobj.style.left);
      //same concept with the vertical position
      if (bottomedge<tipobj.offsetHeight)
          tipobj.style.top=ie? ietruebody().scrollTop+event.clientY-tipobj.offsetHeight-offsetypoint+"px" : window.pageYOffset+e.clientY-tipobj.offsetHeight-offsetypoint+"px";    
      else
         tipobj.style.top=curY+offsetypoint+"px";

	 // alert(tipobj.style.top);
      tipobj.style.visibility="visible"
  }
}

function hideddrivetip(){
  if (ns6||ie){
      enabletip=false
      tipobj.style.visibility="hidden";
      tipobj.style.left="-1000px";
	  //tipobj.style.left="500px";
      tipobj.style.backgroundColor='';
      tipobj.style.width='';
  }
}