To diagnose problems with Thunderbird, try the following:

• Restart Thunderbird with add-ons disabled (Thunderbird Safe Mode). On the Help menu, click on "Restart with Add-ons Disabled". If Thunderbird works like normal, there is an Add-on or Theme interfering with normal operations. You will need to re-enable add-ons one at a time until you locate the offender.

I cannot disable all addons since I need at least Stylish because that is the way I defined the style (as opposed to using userChrome.css).

I do not use any theme other than what is provided by TB.

Using a clean profile with just Stylish installed it appears the style works. But...

Using my full profile works with TB38.7.2 and all its predecessors. This style problem only appeared starting with TB45.

Deleting all the other addons in my full profile except Stylish still doesn't fix the problem. But as I just said that same profile with just Stylish does work in TB38.7.2.

These last two facts may imply there's something corrupt in my full profile that's causing TB45 to fail but not previous TB versions. If this is the case how can I find it? I'm not sure what to look for in the Error Console nor when to look for it. Or do I even look there? My test is to keep the style edit window displayed and change the font-family. It should immediately change the Subject titles font (does using this technique using TB38.7.2) but nothing appears in the Error Console when I do that (cleared the Error Console before editing/saving the style).

Any suggestions other than starting with a clean profile and adding back all my configurations, preferences, etc.?

anon42 said

I cannot disable all addons since I need at least Stylish because that is the way I defined the style (as opposed to using userChrome.css).

Then I suggest you ask the add-on author for a fix, There is nothing wrong with Thunderbird.

I do not use any theme other than what is provided by TB.

If you run Thunderbird in Safe mode you see the theme that Thunderbird provides.

The web page for stylish https://addons.mozilla.org/en-US/thunderbird/addon/stylish/?src=ss has links for a support site and a support email address. Have you tried using them?

As we do not support add-ons here other than Lightning, I see nothing requiring support.

I'm not interested in what the default theme is in TB. It should have no bearing on this problem unless the default TB45 theme is interfering with my specific font style change. But then it should also interfere in a clean profile too but it doesn't.

Stylish is not the problem either. As I said it WORKS using a clean profile and the style I was testing. Also I've since tested with no addons and added a userChrome.css with the same style. The problem still remains with TB45. So, no addons, default style, works in TB's < 45.0 and not in TB45 using my full profile.

In summary it seems to me I think I have some kind of profile problem. So I ask again. Is there some other error log or console to debug this (other than the Error Console)?

At this point I feel no matter what I say here I am not going to receive any real debugging suggestions since you can always pass the buck back to me so long as you know it's not specifically a TB45 problem. I guess I just live with the font the way it is.

You are in the Thunderbird user support forum, asking for developer support in debugging something. Thunderbird does not have a panel for changing fonts or icons, so anything you do to change the appearance is supposed to be done using a Theme.

You are not using a theme, you are using an add-on that wrapps it's own themes.

Basically you are in the wrong place to get answers and your really upset about that.

The documentation on Theme development is here https://developer.mozilla.org/en-US/Add-ons/Themes

That is also going to include whatever debugging information is available to theme designers (You)

If you have a profile issue, we have no idea what files Stylish writes to, what information is stores where or really anything more than it's name, so of course you are not going to get much help untangling how a particular addon might or might not corrupt you profile.

As I said in my previous post I also tried the style just using userChrome.css with no addons (including Stylish) installed. I guess you consider adding a single style as a "theme". So be it.

Ok, we're done here.

This work in Thunderbird to make the unread font red and in an unreadable font. But that is in userChrome.css.

treechildren:-moz-tree-cell-text(unread) {

color: #D50000 !important; font-family: "Blackadder ITC"; }