Thanks — found a defect.
look in wp-topbar.php
There are two places that you have to change this:
echo '<a href="'.$wptbOptions['social_icon'.$i.'_link'].'" target="_'.$wptbOptions['link_target'].'"><img src="'.$wptbOptions['social_icon'.$i.'_image'].'" style="'.trim($wptbOptions['social_icon'.$i.'_css']).'"/></a>';
to this:
echo '<a href="'.$wptbOptions['social_icon'.$i.'_link'].'" target="_'.$wptbOptions['social_icon'.$i.'_link'_target].'"><img src="'.$wptbOptions['social_icon'.$i.'_image'].'" style="'.trim($wptbOptions['social_icon'.$i.'_css']).'"/></a>';
Again, you have to do this in two places.
I will fix it in the next release.
Thanks for finding this!