Not clear about this feature..."drag posts" from where? If you create a post on Express you can schedule it or leave a draft. Is that storing ideas? It sounds as if you could drag images or Quick Notes as ideas for potential future posts. That would be a useful feature.
Thanks for writing to us.
I'd like to inform you that when a post is created & is not scheduled or 'Draft Post' is checked, it comes under the unscheduled section. These posts are considered ideas. Once the creator is satisfied with those posts, they can drag it to the desired date and set the scheduled time for them to post on social media. The posts can also be dragged from the scheduled section to the unscheduled section if the creator wants to return and re-edit the posts as per requirement.
You may check this video for a better understanding of the content scheduler: https://youtu.be/f-vEq7zhMBo?t=1110
I hope this helps you.