Preventing users from deleting threads

[rllmukforum]

IP.board 3.x allowed users to delete their own posts, through usergroup permissions, but would not permit them to delete a post if it was the first in a thread. Allowing them to do so would, of course, delete everyone else's posts in that thread.

It seems that in 4.1 there is no such restriction, and delete post also means delete thread if you're the OP. We are very keen to permit users to delete their own content (not just hide, for numerous reasons), is it possible to revert to the previous functionality?

[n.karshev]

This is the option in member groups, after 60 minutes they cannot (this is my board setting).

• Editing

• Can edit own content?
  On
  The content must not be locked.
• Edit time restriction
  Can edit own content up to minutes after posting  

  or   Unlimited
• Can edit silently?
  Off
  Normally a message will indicate if content has been edited. If enabled, members in this group will be able to hide this message. Staff members who have permission are always able to see the edit.

[rllmukforum]

On 3/4/2016 at 1:15 AM, n.karshev said:

This is the option in member groups, after 60 minutes they cannot (this is my board setting).

• Editing

• Can edit own content?
  On
  The content must not be locked.
• Edit time restriction
  Can edit own content up to minutes after posting  

  or   Unlimited
• Can edit silently?
  Off
  Normally a message will indicate if content has been edited. If enabled, members in this group will be able to hide this message. Staff members who have permission are always able to see the edit.

That covers editing, but I'm looking for deleting. Specifically, this is what I want to enable, which was how it worked under 3.x:

1. Users can delete their own posts (literally delete, not edit all content out)
2. Users cannot delete their own post if they are the topic starter

Really doesn't appear to be any way to enable this feature, which makes sense as 3.x applied the logic without intervention.