[Problem/Bug]: ContainsFullScreenElementChanged is not raised when fullscreen toolbar button is clicked in PDF reader

What happened?

CoreWebView2.ContainsFullScreenElementChanged is not raised when Enter PDF full screen toolbar button is clicked in PDF reader which makes it impossible to display the PDF content in fullscreen.

Importance

Moderate. My app's user experience is affected, but still usable.

Runtime Channel

Stable release (WebView2 Runtime)

Runtime Version

118.0.2088.61

SDK Version

1.0.2164-prerelease

Framework

WPF

Operating System

Windows 10, Windows 11

OS Version

22621.2428

Repro steps

1. Add an event handler to CoreWebView2.ContainsFullScreenElementChanged
2. Open this sample PDF file with WebView2: https://s1.q4cdn.com/806093406/files/doc_downloads/test.pdf
3. Click on the Enter PDF full screen button in the toolbar of PDF reader opened in WebView2

Expected: CoreWebView2.ContainsFullScreenElementChanged is raised so the app can go to full screen.
Actual:

• CoreWebView2.ContainsFullScreenElementChanged is not raised
• PDF reader goes to full screen mode without any way to exit it - e.g. pressing Esc or F11 doesn't work

Regression

No, this never worked

Last working version (if regression)

No response

AB#47289526

Start by reproducing the issue with the sample PDF and an event handler for CoreWebView2.ContainsFullScreenElementChanged, using the listed WebView2 and WPF versions. Compare the PDF reader toolbar action with other fullscreen transitions; done means the event is raised when Enter PDF full screen is clicked and the host can exit fullscreen.