GK Typography Issue Solved ..for me

GK Typography was not working on a current 3.x site that I just finished. After a lot or reading and some debug work I figured out that the issue was the admin side of the plugin not being able to find any templates, so no data was in 'typo_override' to allow $selected to receive the template name or the xml file name. In fact if i set both $template_name and $file manually in gk_typography.php it all worked.
I built the site not from the quickstart but always do this and understand how to add all the files, I have a working version of the quickstart alongside on the same server so could compare. They were the same, one worked, the other did not.
After some more debug work I discovered that the paths were not being set correctly so no valid templates were being found. Just because I read all the issues around using 'DS' I decided to gamble on adding this code:
if(!defined('DS')){
define('DS',DIRECTORY_SEPARATOR);
}
Into the typooverride.php file. It worked, problem went away and I was able to set the required template and xml file.
I do not know why it was not working. My version of gk_quark was not identical to the quickstart, it has different html and layout file changes to give me control over the which pages the wide header worked and some changes to how articles looked, but all the other files were current. I share because this was a frustrating discovery and it might help others.

Thanks for sharing this solution. I hope it will come handy to someone.