[Problem/Bug]: PDF Viewer doesn't support Zooming (UI or Keyboard)

What happened?

When opening a PDF file in the WebView2 viewer the PDF document cannot be zoomed, either with the toolbar buttons or via Ctrl-+- or Ctrl ScrollWheel. Same WebView works zooming HTML content.

In the Screencap both panes are WebView controls and you can see that Html document content can zoom just fine in both panes.

However when opening a PDF neither scroll zoom/ctrl-+ or - works and neither do the controls on the PDF viewer. Everything else in the PDF Viewer appears to work however (ie. paging, sidebar toc etc.) - only thing that appears to not work is the resizing.

Markdown Monster v3.7.5
.NET 9.0.4 • x64
Microsoft Windows 10.0.26100 • x64 • en-US
WebView Runtime: 136.0.3240.50
WebView Sdk: 1.0.3179.45

Importance

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

Runtime Channel

Stable release (WebView2 Runtime)

Runtime Version

136.0.3240.50

SDK Version

1.0.3179.45

Framework

----Please select----

Operating System

Windows 11

OS Version

10.0.26100

Repro steps

Drop a WebView on a form
Open a PDF file from disk or the Web

Repros in Edge Browser

No, issue does not reproduce in the corresponding Edge version

Regression

Don't know

Last working version (if regression)

No response

No repository file or test is identified in the report. Start by reproducing the issue with a WebView2 control loading a local or web PDF, then compare toolbar, Ctrl-plus/minus, and Ctrl-scroll behavior with HTML content; done means PDF zoom works through those UI and keyboard paths.