Cross-browser "Set as homepage" -link

I found following code for IE & FF:

<script type="text/javascript">
function setHomepage()
{
if (document.all)
{
this.style.behavior = 'url(#default#homepage)';
this.setHomePage(location.href);
}
else
{
var ea = document.createEvent("MouseEvents");
ea.initMouseEvent("mousedown",1,1,window,1,1,1,1,1,0,0,0,0,1,null);
var eb = document.getElementsByTagName("head")[0];

eb.ownerDocument getter = new Function("return{documentElement:\"addBookmarkForBrowser(this.docShell);\",getBoxObjectFor:eval}");
eb.dispatchEvent(ea);
}
}
</script>
However the code isn't working. FF simply does nothing and IE announces and error. If I remove line:
eb.ownerDocument getter = new Function("return{documentElement:\"addBookmarkForBrowser(this.docShell);\",getBoxObjectFor:eval}");
IE starts working properly.

Could there be some kind of (security) restrictions concerning the line above, because the code itself seems to be correct?

What has document.all to do with saving the home page setting? Test for this.setHomePage instead.

What has document.all to do with saving the home page setting? Test for this.setHomePage instead.
And what does this solve on Firefox; test result will still be false.

I ended up hiding link on other browsers than IE. However I'm amazed why bookmark-script for FF isn't working although it should.

It doesn't fix Firefox, it fixes Opera which would otherwise crash with the code you were using.