Beginning with version 1.0.1 of the Configuration Component, you can place parameterized text in the custom overlay. In the example HTML below, the text {popuptitle} represents a predefined parameter for the title attribute from the expanders popup image.

<div style="background: black; font-weight: bold; color: white; margin-top: 2em; padding: 1em">
The title attribute of this popup is:<br /><span style="font-size: 150%; color: white">{popuptitle}</span>
</div>

The parameters that may be used are:

1. {popuptitle} - Title attribute from the popup image.
2. {thumbtitle} - Title attribute from the thumbnail image.
3. {thumbalt} - Alt attribute from the thumbnail image.

Placing the HTML code above into the Custom Overlay HTML section of the configuration along with the Custom Overlay Settings pictured gives the following results.

Note that the Popup Caption option in the Captions section of the configuration is set to "ALT attribute from IMG Tag".