When you delete or suppress a Flow topic, there are surprising effects for that topic's posts in the history.

Deleting a topic:

BanjoDog created a topic called "Cats and dogs", with one post.
Admin DannyH deleted the topic using the dropdown menu on the topic header.

Looking at the history, DannyH (admin) sees:
The line about the topic creation is marked as deleted. This is correct.
The line about the first post looks normal, and still has a "delete" action in the menu. This is not correct.
Clicking on the "delete" action for the first post brings up a modal that doesn't do anything and can't be dismissed.

Looking at the history, BanjoDog (non-admin) sees:
The line about the topic deletion is renamed "This topic was deleted by DannyH", and has a link that leads to an error message. The topic name should not change.
The line about the comment is renamed "This topic was deleted by DannyH", and the edit summary has changed to "An unexpected error occurred." It doesn't cross out the timestamp, so it doesn't look deleted. This is all wrong.

Also, both of those history items link to a post that the non-admin user can't see, with an error message:

<flow-error-not-allowed-view-to-delete-topic>
21:54, 17 April 2015 DannyH (WMF) (talk | contribs) deleted topic "Cats and dogs" on Talk:Sandbox (not appropriate (test))

Suppressing a topic:

Suppressing a topic has the same set of issues.

The item about the first post is not marked as suppressed. Also, clicking suppress on the post item brings up a modal that can't be cancelled:

Non-admins still see an item for a topic called "This topic was suppressed by DannyH":

And there's still a link to an error message: