Thanks to Taxonomy_Single_Term, a library created by WebDevStudios, it made my work much easier on creating this plugin.
With Categories Metabox Enhanced, you can:
- Change the built-in Categories metabox/panel to a single term UI, which means replacing the checkboxes with radio buttons or a select drop-down.
- Apply the single term UI to other hierarchical taxonomies in the plugin’s Settings page.
- Customized the single term UI by setting these options:
- Priority and position of the metabox placement.
- Title of the metabox.
- If child-terms should be indenting.
- If adding of new terms from the metabox is enable.