Replace Category Panel in “write post” screen

Hello,

i want to reorder the categories on the “write post” screen, but i got stuck now ?? .

i created a plugin that hides the original “categories” meta-box and adds my custom one.

this works fine, BUT: whenever i assign a category to a post, the box does not stay checked. it DOES save my edits (remove post from category 1, add it to category 2…) but the boxes just don’t stay checked. this is very confusing.

is there a function i missed? how do i tell the plugin to check for the categories a certain post is assigned to and update it?

please help me a little bit, it’s the first plugin i’m writing and i feel pretty stupid, now trying for three days and no success ??

thanks in advance!!