Can't click any element inside an iframe which itself is a part of shadow DOM

[OrestKavnyi]

🐛 Bug Report

Cannot click an element that lies inside an iframe element which itself is a part of shadow DOM.
First I read the shadowRoot property of the shadowHost element using ExecuteScript() method from under driver:
var root = (IWebElement)(driver as IJavaScriptExecutor).ExecuteScript("return arguments[0].shadowRoot");

Then I am able to locate the iframe lying inside that shadowRoot element and switch to it like this:

var iframe = root.FindElement(By.TagName("iframe"));
driver.SwitchTo().Frame(iframe);

Now, I can easily access any element. There is no problem with that:
var btnElement = driver.FindElement(By.CcsSelector("button")); // btnElement contains a valid reference

Now trying to click that element like this btnElement.Click(); throws the WebDriverException saying "unknown error: no element reference returned by script".

An interesting fact is that I can simulate Click with SendKeys(Keys.Enter) invoked from under the element (btnElement in this case). Js click performed in the folowing way:
(driver as IJavaScriptExecutor).ExecuteScript("arguments[0].click();", btnElement);
also works fine.

I also tried switching to earlier versions of Selenium WebDriver (down to 2.39.0) but got nowhere, - I was still able to reproduce the issue.

So, if you have any thoughts/ideas about what might cause the issue, please let me know. I would really appreciate any help!

Environment

OS: Windows 10
Browser: Chrome
Browser version: 91.0.4472.106
Browser Driver version: 91.0.4472.101
Language Bindings version: C#, 3.141.0

[diemol]

There is no support yet for shadow DOM yet in Selenium, please follow #5869 for updates.

As for this issue, it looks more like a question than an issue (given that shadow DOM is not supported yet).

💡 A better way to address this is:

• 📫 Send questions and support requests to the Selenium user group
• 📮 Post them to StackOverflow
• 🗣 Join us in the IRC/Slack channel where the community can help you as well