var xpos = 300;
var ypos = 200;
var step = 1;
var delay = 30
var height = 0;
var hoffset = 0;
var woffset = 0;
var yon = 0;
var xon = 0;
var pause = true;
var gyx = document.getelementbyid("gyx");
var interval;gyx.style.top = ypos;
function changepos() { 
 width = document.documentelement.clientwidth;
 height = document.documentelement.clientheight;
 hoffset = gyx.offsetheight;
 woffset = gyx.offsetwidth;
 gyx.style.left = (xpos + document.documentelement.scrollleft) + "px";
 gyx.style.top = (ypos + document.documentelement.scrolltop) + "px";
 if (yon){
  ypos = ypos + step;
 }else{
  ypos = ypos - step;
 }
 if (ypos < 0){
  yon = 1;ypos = 0;
 }
 if (ypos >= (height - hoffset)){
  yon = 0;ypos = (height - hoffset);
 }
 if (xon){
  xpos = xpos + step;
 }else{
  xpos = xpos - step;
 }
 if(xpos < 0){
  xon = 1;xpos = 0;
 }
 if(xpos >= (width - woffset)){
  xon = 0;xpos = (width - woffset);
 }
}
function start(){
 gyx.style.visibility = "visible";
 interval = setinterval(changepos, delay);
}
function pause_resume(){
 if(pause){
  clearinterval(interval);
  pause = false;
 }else{
  interval = setinterval(changepos,delay);
  pause = true;
 } 
}
start();