// Detect if the browser is IE or not.
// If it is not IE, we assume that the browser is NS.
var IE = document.all?true:false

// If NS -- that is, !IE -- then set up for mouse capture
if (!IE) document.captureEvents(Event.MOUSEMOVE)

// Set-up to use getMouseXY function onMouseMove
document.onmousemove = getMouseXY;

// Temporary variables to hold mouse x-y pos.s
var mouseX = 0;
var mouseY = 0;

// Main function to retrieve mouse x-y pos.s

function getMouseXY(e) {
  if (IE) { // grab the x-y pos.s if browser is IE
    mouseX = event.clientX + document.body.scrollLeft;
    mouseY = event.clientY + document.body.scrollTop;
  } else {  // grab the x-y pos.s if browser is NS
    mouseX = e.pageX;
    mouseY = e.pageY;
  }  
  // catch possible negative values in NS4
  if (mouseX < 0){mouseX = 0}
  if (mouseY < 0){mouseY = 0}  
  
  return true;
}


// vyska okna
function getWindowHeight() {
   if (window.innerHeight)
      /* NN4 a kompatibilní prohlížeče */
      return window.innerHeight;
   else if
   (document.documentElement &&
   document.documentElement.clientHeight)
      /* MSIE6 v std. režimu - Opera a Mozilla
      již uspěly s window.innerHeight */
      return document.documentElement.clientHeight;
   else if
   (document.body && document.body.clientHeight)
      /* starší MSIE + MSIE6 v quirk režimu */
      return document.body.clientHeight;
   else
      return null;
}

// sirka okna
function getWindowWidth() {
   if (window.innerWidth)
      /* NN4 a kompatibilní prohlížeče */
      return window.innerWidth;
   else if
   (document.documentElement &&
   document.documentElement.clientWidth)
      /* MSIE6 v std. režimu - Opera a Mozilla
      již uspěly s window.innerHeight */
      return document.documentElement.clientWidth;
   else if
   (document.body && document.body.clientWidth)
      /* starší MSIE + MSIE6 v quirk režimu */
      return document.body.clientWidth;
   else
      return null;
}