Tooltip question

This in regards to SEO for forums, there are some themes such as the default XenForo one that uses tooltips instead of a regular forum description that is visible on the spot (like how BHW) does.

Is this bad for SEO or does it have the same impact as the standard style?

If you're confused as to what I'm talking about you could check out the official forum for Xenforo and hover over say "Announcements", you will see some text there. I did a Google Search and see that it does indeed show up but I'm wondering if it's weighed any less or not when it comes to the SE picking it up as content.

If the tooltips are implemented via CSS, the text may still be within the tags and therefore useful for SEO. But if the tooltip is implemented out of the HTML structure and using some specialty JS lib, it may not be understood as related to that particular link.