I'm not really worried about the admin side, being able to add new templates all the time, etc. I don't mind if it take a little work to setup...
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Should each template set have specific style sheets?It would be nice, so that you could have different color styles without having one template for each color.
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Should each template set have specific images/image directory?Yes, there is already a mod (
https://www.ubbdev.com/threads/php/showflat.php?Cat=&Board=beta&Number=63767) for specific image directories for each stylesheet, and the directories are specified in the theme.inc.php in this format:
<br />$theme['imagedir'] = "stylesheet1:/imagedirectory, <br /> infopop:/Infopopimages";<br />
You could use something similar.
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Should each template set have specific includes? (headers/footers/javascript)That would be a good future improvement but I think for now it could use the default ones.
Just put a warning on the mod that admin area editing of stylesheets, templates, etc could break things. I can't say I've ever used the admin area to edit the look of my site... It's all done in a text editor on my computer

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