User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/85.0.4183.83 Safari/537.36

Steps to reproduce:

1. Set up any Light theme
2. Open any Custimise toolbar window in TB
3. Observe solid black borders artefacts from the dark mode.

Actual results:

Instead of light theme UI I observe dark theme colours.

Expected results:

The light theme should not inherit dark theme settings.
Let disable DARK theme completely.

What is the exact version number of the Thunderbird with the problem?

(In reply to Alex Ihrig [:Thunderbird_Mail_DE] from comment #1)

What is the exact version number of the Thunderbird with the problem?

Hi! 78.2.1.

I can not confirm this in 78.2.1 on Win 10.

It is still necessary to switch from any Dark Mode over the (included) Light Mode to Standard Mode, to have the light Standard Mode really in white colors. But this is for the complete application - not only for the customize dialog.

Richard will probably understand how it should/does work.

I don't see this on my Win10 with dark system theme and light TB theme. The customize dialog is then light like it should.

Is this the only dialog, that is dark?

(In reply to Richard Marti (:Paenglab) from comment #5)

I don't see this on my Win10 with dark system theme and light TB theme. The customize dialog is then light like it should.

Is this the only dialog, that is dark?

Hi! Not only. Eg, when you are switching on Chat functionality you may also observe black artefacts on the window with the list of chat accounts.

I see also no dark areas in chat. Have you tried to switch to a different theme and back? You don't have a userChrome.css customization?
Maybe you need to try with a new profile.

78.2.2 dark mode turned on randomly. Was on a doct who van gogh tardis theme. I did recently apply css code to thunderbird to turn folders with newly arrived messages red. Some threads turn back from white text to black text upon selection, but settings are still in black. Tried switching to light mode from doctor who theme.

user agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.2.2

last time this happened i lost templates...

(In reply to Koty from comment #8)

78.2.2 dark mode turned on randomly. Was on a doct who van gogh tardis theme. I did recently apply css code to thunderbird to turn folders with newly arrived messages red. Some threads turn back from white text to black text upon selection, but settings are still in black. Tried switching to light mode from doctor who theme.

user agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.2.2

last time this happened i lost templates...

(Koty, you will want a blank line between quoted material and your response)
sorry I wasn't sure how to update this:
if i switch to light mode and then close and reopen it does fix the issue - probably not permanent though?

probably not permanent though?

Have you found it to be permanent?

Hi! After the last 2 updates I see that the situation didn't change a lot, the same bad experience of getting black stripes, black fields, but some other plugins become subjected to the issue, in particular Cardbook:
Please, have a look at this screenshot https://prnt.sc/vk3xqt

Anje, can you reproduce the original comment?

Using 78.7.1 64bit
Windows set up with dark theme for system and apps.
Thunderbird - removed my 'chrome' folder as I do have css effecting folders etc and restart Thunderbird.
Downloaded that Dr Who theme to help with tests.

Using either Dr Who or Thunderbird Light theme to produce a white background theme for Folder Pane, Thread Pane, area of Message Pane only if I select more than one email to show as 'X messages or Conversations and Address Book, I can alter all other areas to display the dark theme with exception of 'Customise' and other pop up windows like 'Search Messages' which follows either TB Light or Dr Who ( shows as lilac!) theme.
Achieved by setting:
Setting Options > General
Language & Appearance
click on 'Colours'
Select: Text as White, Background as Black, uncheck system colours and set the 'Override the colours..etc' to 'Always'.

So, Options, Account Settings, Troubleshooting Information, Addons, Message Pane when I selected individual messages, all now display black background with white text, overridding any messages that contain css.

But the 'Customise' and 'Search Messages' pop up type window always keeps up with the theme selected. So I'm not managing to recreate issues in the pop up windows like 'Customise' and 'Search Messages'.

Note: Print Preview will display problems. as there seems to be a conflict. eg: If 'Message Pane' set up as descibed then Background is Black with White Text, but in Print Preview, the Black background is shown as per Overide setting, but all the font is also black as if the font is following the Light Theme setting. Separate bug 1675367

Language & Appearance
click on 'Colours'
Select: Text as White, Background as Black, SELECT system colours and set the 'Override the colours..etc' to 'Always'.
This reverts everything to the Light theme, thus ignoring the 'override' setting.
Note: if the override the colours setting is selected then it also stops displaying the change of colour to selected option.
eg: If in 'Options' and you have selected 'General', the text will remain Black (if system colours is selected) or White. It does not change colour to show as selected nor any button show as highlighted if hover over. So the override really overrides, this does not occur in the Main UI (Folder Pane, Thread Pane, Customise or Search Messages).

I would advise these settings when using a Light theme.
Menu app icon > Options > General
Under 'Language & Appearance' section
click on 'Colours' button
Select: Text as Black, Background as White, uncheck system colours and set the 'Override the colours..etc' to 'Never'

Request info from reporter.
If you remove the 'chrome' folder from 'profile name ' folder then start Thunderbird and set Options settings as advised above what issues do you still see when using Thunderbird Light theme ?

(In reply to knedlyk from comment #11)

Hi! After the last 2 updates I see that the situation didn't change a lot, the same bad experience of getting black stripes, black fields, but some other plugins become subjected to the issue, in particular Cardbook:
Please, have a look at this screenshot https://prnt.sc/vk3xqt

For cardbook, perhaps you need to talk to those folks ? (I'm not sure)

Seems nobody can reproduce. Whatever it is, only a support case atm. Maybe add-on causing it.

Last update of TB has fixed the issue partially, though the background in the calendar event still remains dark in case of using light theme.