[MlMt] Deleting parent message does not delete children when expanded

[Antonio Leding]

Hello all,

I have found that the delete behavior for parent & child messages is 
different depending on whether or not the message chain is expanded or 
collapsed.

When expanded, only messages that are highlighted are deleted but the 
children remain as is.  If collapsed, then all of the messages that are 
highlighted are deleted but their children are as well.

In essence the app appears to treat a collapsed chain as highlighted if 
the parent is highlighted.

My question to the community is this:  Is this by design or a bug?

Thanks in advance.