I think they need to include a jscript_imagehover.js in the custom folder as currently its only in the template default folder and you need to have this file installed in the jscript folder in your custom folder if using a custom template.

Most people when they use an FTP program such as myself do this on a per folder basis opening the Image Handler folder and just inserting each file carefully one at a time in the respective folders and i wondered why the image enlargement wasn't working so i had a look at source code on the classic theme after switching template and found the reason was the jscript_imagehover.js file.

So for anyone having the same trouble i did then just go to template_default and get this file and put it in your custom folders jscript folder and if there isn't a custom folder just send the whole folder up and it will work.

I think whoever looks after the contribution should include that file in the custom template jscript folder section for download and not just the template default jscript folder section. ( there is currently no custom template jscript folder and thats the problem )

Hope this information helps someone.