Problems with themes and addons should be addressed to the authors of those addons.

Well, that's helpful. The problem is with two addons and so thought it might be more general than specific but if you can't or won't help that's fine I won't bother asking anymore.

I presume you are talking about:

• https://addons.thunderbird.net/en-us/thunderbird/addon/old-icons/

Matt's comment is valid and accurate. Addons are not created by Thunderbird. They are a piece of code written by a person - an author - and they are solely responsible for their addon. If you experience a problem with an addon then you need to communicate with the author. It may be useful information for the author. At the link above, on the right hand side of window, there is a 'Support Email' link you can use to email the person responsible for the add-on.

However, before you go down that route, you mentioned you had previously used other addons for buttons/folders etc. The area of code being manipulated is the same when using addons that perform same type of functionality. So, it is possible there is some conflict in the code - basically one addon is messing up another addon.

Did you fully uninstall the Phoenity Icons and Buttons addons and restart Thunderbird to ensure they had been removed? If no then I would do this first.

The alternative would be remove addons and use the 'userChrome.css' method to insert and use old folder pane folder icons.

Thanks for your reply but if you had read my initial post you would be able to understand that I am having trouble with both; https://addons.thunderbird.net/en-US/thunderbird/addon/phoenity-icons/ and https://addons.thunderbird.net/en-us/thunderbird/addon/old-icons/ not just one of the add-ons. As much as I appreciate what you are saying it seems to me that if I am having the same problem with both add-ons then it is a Thunderbird 'glitch' not anything to do with one of the add-ons so the authors aren't going to be interested in solving a problem which is nothing to do with their particular development. I have uninstalled 'Old Icons,' and restarted Thunderbird and as I said in my initial post the Phoenity icons flash up and then disappear almost instantly so no resolution there. It sounds as if I am a voice in the wilderness here and am not going to get any help or support so I suggest I'll just put up with the problem or try to solve it myself. Great outcome from Mozilla Support.

re :Thanks for your reply but if you had read my initial post you would be able to understand that I am having trouble with both; I know.

Have you completely uninstalled all the addons eg: phoenity and old icons and any other you have installed. then restarted Thunderbird and then download and install 'old icons'

So you only have one of those addons installed at any time - I do not mean just disabled - I mean others are uninstalled before you try another.

It's no good as a test if you had two types or more installed and you only removed one of them, leaving one installed. You have to uninstall all of the addons and restart and then perform a separate download and also make sure you are installing the correct version.

You have not stated that you uninstalled all of them, restarted and downloaded eg: old icons a fresh.

Lets get something very clear. If you have no problems when you uninstall all the addons then the issue is with the addon. All addons have to work with Thunderbird and not the other way around.

It's very obvious, either the addon does not work due to a clash with another addon or the addon is not compatible.

What other addons do you have installed?

it seems to me that if I am having the same problem with both add-ons then it is a Thunderbird 'glitch' not anything to do with one of the add-ons so the authors aren't going to be interested in solving a problem which is nothing to do with their particular development.

You might be surprised. How do they become aware of an issue that requires fixing either in their addon, or Thunderbird if no one reports it it? Addon authors have access to a whole API to modify Thunderbird, they also have access to a dedicated addons developer mailing list where they discuss issues and seek resolution. You assume that these two individuals will simply dismiss your issue out of hand. Why you make that assumption escapes me.

Personally I am somewhat suspicious of the versions each suggests it supports as V102 and 115 are significantly different under the hood in relation to the toolbar. With one of the "new features" of V115 being a new unified toolbar. Perhaps the authors can support both versions in a single addon XPI. I do not know. It would not be the first time I saw an addon marked as compatible with a version in which it did not work. Perhaps in creating their 115 versions they have lost something that allowed it to work in V102

You notice I am guessing, because I am neither an addon author or a user of those addons, that is the best I can do. The authors however know how it works and what to suggest to fix issues. It might be as simple as a problem with oyur video card that can be fixed by changing the hardware acceleration setting. But I really have no specific idea, neither does anyone else in this forum.

It sounds as if I am a voice in the wilderness here and am not going to get any help or support so I suggest I'll just put up with the problem or try to solve it myself. Great outcome from Mozilla Support.

You are still asking the wrong people in the wrong place ,and now you are complaining complaining the support you seek in the wrong place is not meeting your needs. I still suggest you contact the addon authors to get specific assistance.

The authors of both addons offer an email address for you to contact them on the page you linked to in your first posting here.