Settings UI: Can't configure Default Dark+ in the workspace settings if theme is already set in user

[DiegoBM]

Issue Type: Bug

1. Go to User Settings and set a color theme different than the default one, for example "Kimbie Dark"
2. Go to Workspace Settings and set "Default Dark+"

• Expected Result: Use the "Default Dark+" color theme for the current workspace/folder/project
• Current Result: Uses the "Kimbie Dark" color theme for the current workspace/folder/project.

If you make Workspace Settings' color theme point to any color theme other than "Default Dark+", it will work just fine. It seems like the "Default Dark+" color theme is not a color theme itself (even though it seems to have its own and unique syntax and interface styles) but a pointer to "default", and "default" is whatever value that is selected in User Settings.

We should be to be able to use the "Default Dark+" color theme for certain projects, regardless of the color theme selected globally in User Settings

VS Code version: Code 1.40.1 (8795a98, 2019-11-13T16:49:35.976Z)
OS version: Windows_NT x64 10.0.18363

Extensions (4)

Extension	Author (truncated)	Version
numbered-bookmarks	ale	6.2.1
remote-wsl	ms-	0.40.3
cpptools	ms-	0.26.1
material-icon-theme	PKi	3.9.1

(1 theme extensions excluded)

[vscodebot]

(Experimental duplicate detection)
Thanks for submitting this issue. Please also check if it is already covered by an existing one, like:

• [themes] setting for preferred light and dark color theme based on system dark mode setting (Windows/Mac) (#61519)
• Window Title Bar Style = native does not respect dark theme settings (#84453)
• [themes] Debounce color theme selection (#71616)
• Add a setting to specify an alternative theme for copy with syntax highlighting (#59709)

[aeschli]

It's a bug in the settings UI. I says Default Dark+ is the default, which is not really correct when the user settings have a different theme set (maybe Kimbie Dark should get the default label?). So clearing the setting doesn't result in having the Default Dark+ theme.

[roblourens]

Dupe of #58038