Hi folks, long time no see... ;-)
I put together a little tutorial for the full screen random background plugin. I'll try to post it here:
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Step-By-Step to Random Full Background Images
by Sawatzki
1:     First of all, there are some files that have to be copied to your server:
    1.1: The Indexhibit-Plugin "plugin.random_full_background.php"
    --> This file goes into the folder "/ndxz-studio/site/plugin/"
    1.2: The javascript-file, that resizes the images: "full_background.js"
    --> This file goes into the folder "/ndxz-studio/site/js/"
    
    1.3: A folder containing the images to choose from.
    --> Create a folder called "bgbig" on the root level* of your website and upload some images to it.
    * "root level" = where you installed indexhibit.
    --> If you already have a folder with images you want to use, read the comment in the code at step 2.A.2.
2: Now, we have to modify both our main site "index.php" and "style.css". These are located inside your theme folder.
If you never changed your theme in the advanced settings of Indexhibit, you are still using the standard theme called "eatock".
If you did change it through indexhibit, it will propably be called "sample". If you made your own theme folder, then that's the one we will look at...
    2.A: Edit "index.php"
    
        2.A.1: Open "../ndxz-studio/site/(your theme)/index.php" in your favorite editor
        and find the end of thesection.
        Insert the following code just before "< em >":
        2.A.2: Two lines down, you will find the opening body-tag.
        
        Insert the following code just after "< em >":
            
2.A.3: Find the tag at the end of the file and insert the following code just before it:
            
    
        
    2.B: Edit "style.css"        
        2.B.1: Open "../ndxz-studio/site/(your theme)/style.css" in your favorite editor
        and add the following lines to it a line before "#menu { ...":    
            
            #the-background {
                position: fixed;
                overflow: hidden;
                z-index:1;
                width: 100%;
                height:100%;
                top:0;
                left:0;
            }
#wrapper {
            position: absolute;
            z-index: 2;
            width: 100%;
            height: 100%;
            top: 0;
            left:0;
            }
That's it. It should work now. Hopefully... no guarantee... ;-)                    
P.S. The file ../ndxz-studio/site/(your theme)/ie.css should be modified accordingly, I didnt have time to do this yet...