More control over where the popup appears

[Salubritas]

I would like finer control over where the popup appears. The 'selector' option is OK but I could do with the option to exclude elements which are marked up with a specific class.

e.g. if I set my selector to 'body' then within the body I have

<p class="no-sharethis">blah blah</p>

Then the popup would not trigger when 'blah blah' is selected.

Thanks