Custom corners use the technique from Roger Johansson. He describes how to build the graphices on his page "customising_custom_corners_and_borders"
The Moodle implementation does not use JavaScript as describd in Roger Johansson's documentation. Moodle adds all neccessary divs to the pages when the option "$THEME->customcorners = true;" is set in config.php.
Custom_corners uses the Chameleon engine. You must not write hooks as comma separated lists of elements like
td#middle-column div.bt,
div#middle-column div.bt {
...
}
in Chameleon enhanced themes because the Chameleon engine can't handle these comma lists.
Please write two seperate statements instead.
td#middle-column div.bt {
...
}
div#middle-column div.bt {
...
}
A Moodle Theme from Urs Hunkler, unodo.