Do not remove the element having focus in Internet Explorer 9!

I had to fix this weird bug today, where only in IE9 the entire page would freeze suddenly. The only way to get anything done was to select some text or scroll a scrollable area. I was creating an input text field, then, when pressing enter, I would do something with the value and remove the element.

It appears that in Internet Explorer 9 it is wrong to remove the element that holds the focus. Use window.focus(); before you do that.