When you start the reordering, we basically copy the list of all the current pages and perform the reordering on that. Once you are done with the reordering, we update the actual order with the one from the copy. That's what allows you to cancel the reordering again.
Now, when you are reordering, you are still able to insert blocks and pages via the top toolbar. However, you won't see any new pages in the reordering panel because the copy hasn't been updated.
Some possible options here:
- Disable/Hide all the buttons in the top toolbar when reordering.
I think this makes the most sense. When reordering, no one page is selected, so it doesn't make sense to have the top toolbar appearing.
Working On This If That's Alright
Hi @swissspidy,
If it's alright, I'm going to work on this.
See gif at #2266 for testing instructions / desired outcome
Thanks, @swissspidy
Verified in QA - Inserter and block options disabled when reordering:

Most helpful comment
I think this makes the most sense. When reordering, no one page is selected, so it doesn't make sense to have the top toolbar appearing.