Alexei Barantsev Reporter
	Description • 7 years ago

User Agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/62.0.3202.75 Safari/537.36

Steps to reproduce:

Run this snippet of code using Selenium 3.7.0 and geckodriver 0.19:

FirefoxOptions options = new FirefoxOptions();
options.setCapability(CapabilityType.OVERLAPPING_CHECK_DISABLED, true);
FirefoxDriver driver = new FirefoxDriver(options);
driver.get("https://output.jsbin.com/komihom");
driver.findElement(By.id("under")).click();


Actual results:

org.openqa.selenium.ElementClickInterceptedException: Element <div id="under"> is not clickable at point (70,70) because another element <div id="over"> obscures it



Expected results:

No exception expected, the driver should click the topmost element at point.

Works well in release channel (56.0.1). Used to work in Nightly before 2017-11-03.

	Henrik Skupin [:whimboo][⌚️UTC+1]
	Comment 1 • 7 years ago

What kind of capability is `OVERLAPPING_CHECK_DISABLED`? I cannot see it in the WebDriver specification, and as such it is not taken into account for the webdriver compliant click method as introduced with bug 1321516.

Also this was working before with geckodriver and Firefox up to version 57 because no interactability checks have been performed at all.

Andreas, I assume this is a relict from the old Firefox driver, and we won't longer support that?

	Andreas Tolfsen ❲:ato❳
	Comment 2 • 7 years ago

(In reply to Henrik Skupin (:whimboo) from comment #1)

> I assume this is a relict from the old Firefox driver, and we
> won't longer support that?

I’ve never heard of OVERLAPPING_CHECK_DISABLED before.  I
don’t know what it is.

The basic principle we follow is that if something is not in the
specification, we won’t implement it.

	Alexei Barantsev Reporter
	Comment 3 • 7 years ago

This capability was supported by legacy Firefox driver. It's OK to close this issue if geckodriver is not going to support it.

	Andreas Tolfsen ❲:ato❳
	Comment 4 • 7 years ago

Out of curiosity, what is it and what does it do?  Where is it documented?

	Henrik Skupin [:whimboo][⌚️UTC+1]
	Comment 5 • 7 years ago

https://github.com/SeleniumHQ/selenium/blob/6c27816c9b90e642228b43fb977a99c1b17a402e/java/CHANGELOG

v2.52.0
=======
Firefox:
  * Implementing a capability that disables overlapping checks - "overlappingCheckDisabled"

It was added by:
https://github.com/SeleniumHQ/selenium/commit/ab994066135f81b43d6ebed93bb398e7c7d064c1

I cannot find an issue nor PR for that landing.

As it looks like it was only added to Firefox, and no other browser. No idea, which purpose that has. But Alexei should be able to tell us.

Given that this is not covered by the spec, lets close the bug.

	Jason Juang (:juangj)
	Comment 6 • 7 years ago

IIRC, the history is that FirefoxDriver did not check if an element was overlapped by another element. If you asked to click an element, but the point at which the click would occur was covered by another element, then your target element (the bottom element) would receive a click event anyway, even though that was impossible for a user to have done.

ChromeDriver checked for that overlapping condition and made it an error to try to click the bottom element. ("Element is not clickable at point (x, y). Other element would receive the click:"

Alexei added code to FirefoxDriver to implement that check, but because that would break existing tests, he also introduced a capability for users who wanted to preserve the old behavior. At the time, the legacy FirefoxDriver was the only major driver that omitted overlapping element checks.

The WebDriver spec does say that this should be an error, so I think you are correct to just declare that this is intentionally unimplemented.

	Henrik Skupin [:whimboo][⌚️UTC+1]
	Comment 7 • 7 years ago

I see. Thank you for the explanation, Jason! Good to see that our native implementation is in place by default now.

	Alexei Barantsev Reporter
	Comment 8 • 7 years ago

Yes, I know the history behind this capability :)

In the days of yore we used to have so called "native" events in Firefox driver. These "native" events were simulated on OS level. Obviously, they did not check element overlapping. The *topmost* element at point received the event (unlike Jason stated).

At the same time, Chrome driver used to check element overlapping.

While implementing "synthesized" events in Firefox driver we couldn't decide which party to join to. So we've foung a solution that would satisfy both parties. Without a capability Firefox driver checks overlapping. If it breaks your tests developed for "native" events, you can set OVERLAPPING_CHECK_DISABLED capability and make it more backward compatible.

	Jason Juang (:juangj)
	Comment 9 • 7 years ago

Oh yes, that's true for native events. For synthesized events, we used to have a test that showed that the bottom element received the click. Naturally, that made things even more confusing.

... Well, at any rate, we can all be happy that this discrepancy was cleared up by the spec :)