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Cosimo is the acronym for “Change Of Scene Image Many Often”. Static background images are boring very quickly. Cosimo wants to avoid this. 
Users of <a href="https://wordpress.org/extend/plugins/nextgen-gallery/" rel="ugc">NextGEN gallery</a> can prepare a gallery of wallpapers and use them on Cosimo settings. 
A string in the glob-style format, for example, *69*Summer, Spring?-Break*, etc. can also select images from the media library. 
The change interval may following a number of page views or time (minutes, hours, days, weeks, months, years done). 
The background image is used on the site about inline CSS, as in this example:
<blockquote>
body {background-image:url(http://…../wp-content/uploads/bg-superduper.jpg) !important;} 
 Cache tools such as <a href="https://wordpress.org/extend/plugins/wp-super-cache/" rel="ugc">WP Super Cache</a> can cause additional delays, especially in the range of hours. If necessary, the plugin could be expanded to also change the Header image. User feedback is welcome.
</blockquote>

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