I am using jQuery plugin (http://plugins.jquery.com/project/lwRTE) and oddly enough in IE8 when I close the RichText Editor (which opens within a lightbox), I am unable to select any text on the document.
This is a peculiar case and happens when TextArea of RichText Editor already contains some text and I 'give' focus to the TextArea and close the lightbox. However, when I give focus to the TextArea(which is an iframe with deisgnMode='on' in reality) and select the text inside it, after closing the lightbox, text selection works as usual.
There are several ways a document can be made not selectable and one of them is returning false in onstartselect() or in onmousedown(). So I made sure that none of my code returns 'false' from the event handler and yet the document stays unselectable. lwRTE plugin works by converting the TextArea content to a document within iframe and setting designMode='on' for the iframe.