[WebDriver] keyup events are not delivered when any modifier key is involved

[Qianlang Chen]

Suppose we start with this Python 3 code (with Selenium 4 installed):

    import time
    from selenium.webdriver import Safari, Keys
    driver = Safari()
    driver.get(".../some/webpage.html")
    time.sleep(2)

If we do

    driver.find_element("tag name", "body").send_keys("abc")  # Case 1

Then, for each of the keys A, B, and C, a `keydown` even is sent and a `keyup` event immediately follows. This is correct and is what happens even if the browser window loses input focus.

However, if we do

    driver.find_element("tag name", "body").send_keys(Keys.COMMAND, "a")

Then,

   - If the browser window is focused, a `keydown` for Command is sent and a `keydown` event for A are sent. No `keyup` events are sent at all. (Case 2)

   - If the browser window is NOT focused, a `keydown` for Command is sent, and that's it. (Case 3)

If we log in the target webpage details of the events it receives, this is what we see:

   - Case 1:
       {"type":"keydown","key":"a","metaKey":false}
       {"type":"keyup","key":"a","metaKey":false}
       {"type":"keydown","key":"b","metaKey":false}
       {"type":"keyup","key":"b","metaKey":false}
       {"type":"keydown","key":"c","metaKey":false}
       {"type":"keyup","key":"c","metaKey":false}

   - Case 2:
       {"type":"keydown","key":"Meta","metaKey":true}
       {"type":"keydown","key":"a","metaKey":true}

   - Case 3:
       {"type":"keydown","key":"Meta","metaKey":true}

Case 1 is correct. The correct log for both Case 2 and Case 3 should be:
       {"type":"keydown","key":"Meta","metaKey":true}
       {"type":"keydown","key":"a","metaKey":true}
       {"type":"keyup","key":"a","metaKey":true}
       {"type":"keyup","key":"Meta","metaKey":false}

And this is the output of Chrome/chromedriver, regardless of whether the window is focused.

[Qianlang Chen]

Created attachment 471653 [details]
The webpage in a sample test case: host this on `http://localhost:8000`

[Qianlang Chen]

Created attachment 471654 [details]
The Python test driver

[Radar WebKit Bug Importer]

<rdar://problem/129627106>