fullscreen on lightbox

Hello.

(Sorry for my poor English!)

I want to add a fullscreen-button in Lightbox, while viewing images attached.

I have done the following steps:

1- Admin CP > Appearance > Styles > Default Style > Templates > lightbox:

After:

Code:

<span class="avatar" id="LbAvatar" style="display:none"><img alt="" /></span>

ADD:

Code:

<script>
function launchIntoFullscreen(element) {
  if(element.requestFullscreen) {
  element.requestFullscreen();
  } else if(element.mozRequestFullScreen) {
  element.mozRequestFullScreen();
  } else if(element.webkitRequestFullscreen) {
  element.webkitRequestFullscreen();
  } else if(element.msRequestFullscreen) {
  element.msRequestFullscreen();
  }
}
</script>

2- Admin CP > Appearance > Styles > Default Style > Templates > lightbox:

After:

Code:

<a class="OverlayCloser" title="{xen:phrase close}"><span>X</span></a>

ADD:

Code:

<a onclick="launchIntoFullscreen(document.getElementById('LightBox'));">Fu</a>

3- with file-manager Open: xen\js\xenforo\xenforo.js:
Replace:

Code:

closeSpeed:0,closeOnResize:!0,

with:

Code:

closeSpeed:0,closeOnResize:0,

But when I click on the fullscreen-button, Photo not cover the entire screen. I think after Fullscreen, width and height of the image, imageContainer must be re-calculated by JavaScript.

(Plese See Attachments)

Thanks.