from what I read Google simply applies a label. if that is correct. Right click the account in the folder pane and select settings. in server settings for the account click the advanced button and ensure that show only subscribed folder is not ticked.

Now he categories should appear as folders. I think. At least I made important and Starred appear that way.

Thank you for the suggestions.

However, the categories still don't appear. By the way, I think that "Important" and "Starred" are system labels, not categories.

Any other thoughts?

I have just checked gmail webmail account 'Settings' > 'Labels'. It shows very clearly in the gmail account that the Categories section does not have the options to 'show in imap' as the 'Labels' them selves have this option.

I would deduce from this that it is is not a Thunderbird issue, but gmail does not offer the option.

Located this same question on google forum:

• https://productforums.google.com/forum/#!topic/gmail/hvh_zh8E0hM

They suggest you use a workaround by using filters.

Very helpful. So, the solution lies in using filters in gmail.

This is just the information I need. Thank you so much for your help. You are a wonderful resource for users like me.