How to add a custom widget at the post-new.php?

You can’t add a widget to the Add New Post page. Widgets belong in Appearance->Widgets.

Why? i need that. there is a possibility to add widget on the dashboard. i need something like that, but on a post new page.

Widgets are for the front end of a site – not the back end. What is it that you are trying to do?

i need to have some custom fields, but i have to do some actions with that fields, before they go to the db.

i found.