I'm writing a plugin which only purpose is to add the following code around a selected text in the editor.
<a href="#" onmouseover="setDivVisibility(1);setDivContents('Informative text.');" onmouseout="setDivVisibility(0);"> tooltip / hover text </a>
Re: Writing a Hover / Tooltip plugin
Feel free to add any thoughts you may have on this. Anything at all that might be relevant to the matter.