The slider also gives you the possibility of displaying thumbnails, which can be images or HTML content. You can specify the image in the Thumbnail Image section and the HTML content in the Thumbnail Content section. Also, you can reference the thumbnail image in the Thumbnail Content section using the [sp_thumbnail_image] shortcode.
In order to enable the thumbnail scroller, you will need to set the 'Thumbnail Type' option to 'Scroller'.
If the thumbnail image is not specified, the slider will automatically create a thumbnail image based on the main image set for the slide, by minimizing and cropping it.
Just like with the slide image, you can choose an image from the Media Library or you can manually insert its path. You also have the option to specify some text for the 'alt' and 'title' attribute. The specified 'alt' text will be used as a thumbnail caption and the 'title' text will be displayed in a tooltip.
NOTE: If the image boxes show 'Image Not Found', that's an indication that TimThumb is not allowed to run properly. For troubleshooting this problem, please refer to the 'Troubleshooting' chapter.
NOTE: The default TimThumb settings will not allow you to load external images. In order to enable this functionality, you will need to open the 'timthumb-config.php' file (/wp-content/plugins/slider-pro/includes/timthumb/timthumb-config.php), set the 'ALLOW_EXTERNAL' variable to true and then, in $ALLOWED_SITES, specify the external domain where the images are located. If you want to load external images from any domain, you can set the 'ALLOW_ALL_EXTERNAL_SITES' variable to true.