When creating a new message (URL http://www.dndbeyond.com/private-messages/send) if you type anything into the Recipients text field, a spinner shows at the right edge of the input.

The input in question is <input type="text" name="fc5b11392c6b9bd65963528ee05490a15" id="field-recipients" value="" class="recipients delimited ac_input valid" size="64" data-validation-duplicate="true" data-delimiter=";" autocomplete="off">

and when the spinner is showing, it has the extra class of "ac-loading" which does not go away. I assume this is to generate a list of users who fit the already entered characters? This would be a handy feature if so, but if not, then the spinner does not make sense.