title: window.open throws invalid argument in IE7-8-9b
body: <p>I don't know enough about javascript to figure out why the line in this script that begins  &quot;window.open...&quot; throw an invalid argument error in IE7-8-9b. Works fine in Firefox and Webkit.</p>
  <p>(The script is invoked with an <code>onclick=&quot;share.fb()&quot;</code>in a html link and pops up a new browser window to share at FB and Twitter).</p>
  <pre><code>var share = {
      fb:function(title,url) {
      this.share('http://www.facebook.com/sharer.php?u=##URL##&amp;t=##TITLE##',title,url);
      },
      tw:function(title,url) {
      this.share('http://twitter.com/home?status=##URL##+##TITLE##',title,url);
      },
      share:function(tpl,title,url) {
      if(!url) url = encodeURIComponent(window.location);
      if(!title) title = encodeURIComponent(document.title);
      
      tpl = tpl.replace(&quot;##URL##&quot;,url);
      tpl = tpl.replace(&quot;##TITLE##&quot;,title);
      
      window.open(tpl,&quot;sharewindow&quot;+tpl.substr(6,15),&quot;width=640,height=480&quot;);
      }
      };
  </code></pre>