Currently, when you select one or more posts via the admin wrench, you get the modal below. This works well for the offered options, but if you want to move the posts into a new personal message you have to jump through some extra hoops, some involving undocumented features:
using + new message on the modal, create new message first, which automatically includes the users and groups required
identify the message topic ID from URL (copy to clipboard)
using admin wrench, select posts to move, then select move to existing topic, then type in the topic ID (or paste from clipboard)
I think it would be very handy to instead see a “Move to new message” option here, which would start a new message including the same users and groups containing the selected posts. It would work similarly to the
modal, create new message first, which automatically includes the users and groups required