It is indeed a bug, for which I apologize. To fix it, please download this file from my repository, unzip it, and upload the contained “index.php” file into the following directory on your server: /wp-content/themes/Ikebana/includes/option-tree/
replacing the existing file. Then refresh the Theme Options page.
I’ve double-checked the child theme for Ikebana, and it seems to be working well. Please tell me:
– are you using the child theme included into the theme package? (the “Ikebana-child” folder)
– into which directory did you upload the “Ikebana-child” folder?
please note that individual background colours were introduced since theme version 1.2 – thus if you are using an earlier version, please update first; the background colour can be set in the “Background Color” meta box in the post editor mode (the box is situated to the right of the main text edit area).