This line will result in `NaN` in IE7-8, which _do_ support `obj.getBoundingClientRect()` but _not_ `window.pageXOffset` (`undefined`), ergo, e.g. `4 + undefined - 3` &rarr; `NaN`).  Additionally, the `doctype` value (or lack thereof) can also affect which property to query for the value (ugh!). :-1:

I believe the corrected version would be as follows:
```js
var pageXOffset = window.pageXOffset;
var leftBorderWidth = document.documentElement.clientLeft;
if (typeof pageXOffset !== "number") {
    pageXOffset = document.documentElement.scrollLeft;
    if (!pageXOffset) {
      pageXOffset = document.body.scrollLeft || 0;
      leftBorderWidth = document.body.clientLeft || 0;
    }
}
info.left = rect.left + pageXOffset - leftBorderWidth;
```