Bug 259272 – Click event not dispatched on iPad on a specific domain

• Component: UI Events
• Status: RESOLVED CONFIGURATION CHANGED

[Gianluca Frediani]

Created attachment 467059 [details]
Issue reproduction on iPad simulator

We have an issue with a custom dropdown component, where the click event is not dispatched when the user taps on a menu item, only on iPad when the site is displayed in desktop mode and only on a specific domain.

The issue is present on this page: https://support.watch.nba.com/hc/en-us/requests/new. If the user selects an item from the dropdown, nothing happens. We debugged the issue using the DevTools, and it turned out that Webkit is not emitting the click event when the user taps on a menu item.

The website is built using a SaaS platform, and the same component works well on other instances deployed on different domains. It works well also on iPhone, iPad when the site is displayed in mobile mode and on macOs. 

We found that there is a special handling of mouse events for the specified domain in the Webkit source code: https://github.com/WebKit/WebKit/blob/02196ebd1929a498ae53c4b689d78312094cd0dc/Source/WebCore/page/Quirks.cpp#L424 and we are wondering if this can be the cause of the issue.

I attach a video recording made with the XCode iPad simulator with a reproduction of the issue. The same component is used in two different domains, and the tap is not working on the nba.com domain, but it is working on the other one.

[Ahmad Saleem]

@Karl - it could be quirk stuff, so CCing you.

[Karl Dubost]

Thanks Ahmad.

Gianluca Frediani,

So to test if shouldDispatchSimulatedMouseEvents is the source of the issue, these are the steps to test. 

1. Connect an iPad to a Mac computer
2. Open Safari Technology Preview  (173) (with Developer Settings activated)
3. Open Safari on the iPad
4. On Safari Technology Preview, in Develop Menu, You should see the iPad device and if you hover the icon you will see the list of tabs in Safari on the device.
5. Select the one for the nba website.
6. A Web Inspector window will open for the nba site.
7. on the top left of this web inspector window, there is a cross-hair icon, and just beside a slightly square icon which looks like a device. Click on it.
8. It will display a drop down menu with one of the items being: "Disable Site-Specific Hacks". check the box.

This will disable the Quirks, including shouldDispatchSimulatedMouseEvents.

Re-test what you were doing, does it work this time without the Quirk?
If yes, we have the source of the issue. 
If not, this is something else to investigate.

I opened a new bug for it on webkit 
we already have a radar to remove it rdar://107636342
I was planning to remove the Quirk in the next couple of weeks. 
Our latest tests showed us that it seems not necessary anymore.

[Karl Dubost]

The WebKit bug to remove it is Bug 259332

This Quirk was initially added because of rdar://58804360 or Bug 209829

[Karl Dubost]

(I will be on holiday for most part of July, but I can double check again at the beginning of August)

[Gianluca Frediani]

Created attachment 467072 [details]
Screen recording with hacks disabled

Screen recording showing that the issue is solved by disabling site-specific hacks

[Gianluca Frediani]

Hi Karl,

I tested it again in the simulator following your suggestions, and it seems that disabling site-specific hacks is solving the issue, I attached a screen recording that shows that

[Radar WebKit Bug Importer]

<rdar://problem/112769665>

[Karl Dubost]

In the process of a fix. 
https://github.com/WebKit/WebKit/pull/16472

[Karl Dubost]

The fix has been merged to the trunk.
It will be available in a future release.