RCTSharedApplication().appearance = appearance; makes the window responsive to OS theme changes

[ospfranco]

Environment

npm ls react-native-macos: 0.79

Steps to reproduce the bug

Change the OS theme twice. First time it works. Second time RN app is stuck in the value it changed to.

Expected Behavior

Correctly switched themes

Actual Behavior

It's stuck.

The issue is here:

https://github.com/microsoft/react-native-macos/blob/main/packages/react-native/React/CoreModules/RCTAppearance.mm#L169

By setting the NSApp.appearance after the first change, the app stops being responsive to changes. It needs to be nil for the propagation to suceed. Commenting it out fixes the issue but probably breaks other stuff underneath

Reproducible Demo

None :)

Additional context

No response

[Saadnajmi]

@ospfranco with #2729 do we still have this bug? I realize I wasn't paying attention to whether this was fixed. I can backport that to 0.79 if it helps

[ospfranco]

yes, facebook#2779 is just a fix for the warning. This is a real error. Once appeareance is set, OS theme changes are broken.

[Saadnajmi]

yes, facebook#2779 is just a fix for the warning. This is a real error. Once appeareance is set, OS theme changes are broken.

Do we set it outside of setColorScheme()? My feeling is, if you use that API you are opting out of using the OS theme unless you can call it with nil or "unspecified" or something like that.

[ospfranco]

uh... a recap of my description from discord:

• Change the theme via System Settings app
• An event is fired inside of RN, don't know which path it takes but it ends up calling setColorScheme, WITHOUT me having called the function
• Now appeareance is set, so further events triggered they all have the same value. Effectively locking the theme.

[Saadnajmi]

uh... a recap of my description from discord:

• Change the theme via System Settings app
• An event is fired inside of RN, don't know which path it takes but it ends up calling setColorScheme, WITHOUT me having called the function
• Now appeareance is set, so further events triggered they all have the same value. Effectively locking the theme.

Sorry.. thanks for the recap.