How to custom the Categories meta-box in the panel adding a post! see this url for the picture :https://i.sstatic.net/UkmL4.jpg , I mean here, I have added a custom post,I need the administrator to post a new post without the ability to use the top level categories and also,he can just chose only one category, no more than one category!Anyone can help me, I'm working over for this! thanks for any help!