`set_theme` does not change the theme.

[wyhaya]

Describe the bug

.with_theme(Theme::Dark)
// or
.set_theme(Theme::Dark)

Returned Ok(()), but nothing changed.

Steps To Reproduce

// winit example
let webview = WebViewBuilder::new()
      .with_url("https://tailwindcss.com/")
      .with_theme(Theme::Dark)
      .build_as_child(&window)
      .unwrap();

// or

let webview = self.webview.as_ref().unwrap();
webview.set_theme(Theme::Dark);

// We use `tailwindcss.com` for testing because it uses the auto theme.

Expected behavior

The theme should be updated and return Ok

Screenshots

theme.mov

Platform and Versions (please complete the following information):
OS: Windows 11, Windows 10
Rustc: 1.91.1

Additional context

This is a bug I found in Tauri. When I call app.setTheme, nothing happens, so I came here.

✅ macOS
✅ Linux
❌ Windows

I think it used to be good because it worked fine before, but I'm not sure when it broke.

[wyhaya]

Update:

✅ Windows 11 latest (x86)
❌ Windows 11 latest (Arm/Virtual)
❌ Windows 10 latest

Webview2 version (142.x) meets set_theme requirements and returned Ok(()), but nothing happens.

[FabianLars]

I didn't do any investigation yet but with your last comment this really sounds like an upstream issue. I tested this API literally 2 weeks ago and there it was working (if you used wry's and tao's theme setter together) 🤔