mac: osr: pdf: mouse wheel stops working after a chain of actions with scrollbars

[ujpv]

Describe the bug Mouse wheel stops working after a chain of actions with scrollbars

To Reproduce Note: It's not the only way to reproduce. It's the only way I managed to document. Steps to reproduce the behavior:

1. Run cefclient --off-screen-rendering-enabled. Don't scroll.
2. Open a pdf file in the browser. (e.g. https://www.africau.edu/images/default/sample.pdf). Don't scroll.
3. Put the mouse pointer over the vertical scrollbar. Perform scrolling with the mouse wheel. It works.
4. Perform scrolling by moving the vertical scrollbar thumb. It works.
5. Observe not working the mouse wheel scrolling. Scrolling by scrollbars keeps working.

Expected behavior Both the mouse wheel scrolling and scrollbars work.

Screenshots

https://github.com/chromiumembedded/cef/assets/5990804/b5cab015-b863-42f5-986e-ec965ee29ab6

Versions (please complete the following information):

• OS: MacOS 13.4.1
• CEF Version: 111.2.7, 113.3.5, 116.0.24. Didn't try other.

Additional context Does the problem reproduce with the cefclient or cefsimple sample application at the same version? yes Does the problem reproduce with Google Chrome at the same version? no Add any other context about the problem here. For me it's 100% reproducible if I do the exactly the same actions from To Reproduce. Probably it might be somehow related to: #3153 #2949

[amaitland]

Have you tested on any other OS?

Another potentially related OSR PDF Scroll issue is https://github.com/chromiumembedded/cef/issues/3271

[ujpv]

I've just tried on Windows. It's not reproduceable. Will try linux later

[ujpv]

Can't reproduce on linux as well. It's something macos specific.

[SoulsideJourney]

I have the same problem on Windows 10 19045.3570, CEF 118.6.80