Bugzilla

(In reply to gene smith from comment #3)
> Another outlook/exchange imap issue:
> Create a folder a/b/c
> You get two ghost folder a and b and a normal folder c. You can't copy messages to a or b which is expected (they are "no select").

I see the same - using gmail.

> Now delete folder 'a' to Trash (which renames it). 

I cannot delete my equivalent of 'a'  - the top level 'no-select' folder because Thunderbird is not actually displaying it. 
In folder Pane, I only see 'b' no-select with normal sub folder 'c'. This I discovered when I renamed 'b' aka 'Testing' to 'Testing me' which subsequently killed/deleted  'b' upon restart of Thunderbird.

(In reply to gene smith from comment #3)
> Another outlook/exchange imap issue:
> Create a folder a/b/c
> You get two ghost folder a and b and a normal folder c. You can't copy messages to a or b which is expected (they are "no select").

I see the same - using gmail.

> Now delete folder 'a' to Trash (which renames it). 

I cannot delete my equivalent of 'a'  - the top level 'no-select' folder because Thunderbird is not actually displaying it. 
In folder Pane, I only see 'b' no-select with normal sub folder 'c'. This I discovered when I renamed 'b' aka 'Testing' to 'Testing me' which subsequently was killed/deleted  'b' aka 'Testing me' upon restart of Thunderbird. 



In Thunderbird
Set 'IMAP server directory : [Gmail]'
user_pref("mail.server.server1.server_sub_directory", "[Gmail]");

I do use this to hide the [Gmail] folder. But I do notice the 'INBOX' no-select folder is also hidden which is desirable as I only want to see Inbox subfolders under the real 'Inbox' folder.  So I presume the same code is not displaying the first 'Testing' no select folder as well.
Maybe set up in bug 1818592