Use this template to create a popup window that is displayed when the mouse
is over part of the page. This template has two parameters:
<ul>
<li>`mouseover` - This is the text or other content that triggers the
popup.
<li>`popup` - This should be the content of the popup window. It can be
anything, even images or a whole little wiki page, but should not be too
large for good usability.
</ul>
Note that browsers that do not support the CSS will display the popup
inline in the page, inside square brackets.

[[!templatebody <<ENDBODY
<span class="popup"><TMPL_VAR mouseover>
<span class="paren">[</span><span class="balloon"><TMPL_VAR popup></span><span class="paren">]</span>
</span>
ENDBODY]]