Bug 188561 – mouseenter and mouseleave events don't get dispatched even when there is a capturing event listener for a slot ancestor

• Status: RESOLVED
• Resolution: FIXED
• Component: UI Events

[Olli Pettay (:smaug)]

Created attachment 347090 [details]
testcase, move mouse to top left corner, open console and reload and move mouse per instructions

Per UIEvent spec, mouseenter/leave are composed events, so they do propagate from shadow DOM to host.
But, assuming I'm reading the code right, the optimizations in EventHandler.cpp make mouseenter/leave handling depend on whether there are capturing event listeners, even though the listener on host can be
bubbling listener, since when event is handled at that level, it is AT_TARGET, and all the listeners should be called.

https://trac.webkit.org/browser/webkit/trunk/Source/WebCore/page/EventHandler.cpp#L2529

[Ryosuke Niwa]

(In reply to Olli Pettay (:smaug) from comment #0)
> Created attachment 347090 [details]
> testcase, move mouse to top left corner, open console and reload and move
> mouse per instructions
> 
> Per UIEvent spec, mouseenter/leave are composed events, so they do propagate
> from shadow DOM to host.
> But, assuming I'm reading the code right, the optimizations in
> EventHandler.cpp make mouseenter/leave handling depend on whether there are
> capturing event listeners, even though the listener on host can be
> bubbling listener, since when event is handled at that level, it is
> AT_TARGET, and all the listeners should be called.

The bubbling event listeners are checked as we walk up the ancestors:
https://trac.webkit.org/browser/webkit/trunk/Source/WebCore/page/EventHandler.cpp#L2571

The bug we have is that we're not walking up past the shadow root here.
We also need to make these events not-composed per https://github.com/w3c/uievents/issues/208

[Ryosuke Niwa]

Created attachment 349229 [details]
Fixes the bug

[EWS Watchlist]

Comment on attachment 349229 [details]
Fixes the bug

Attachment 349229 [details] did not pass mac-ews (mac):
Output: https://webkit-queues.webkit.org/results/9136486

New failing tests:
fast/events/shadow-event-path.html

[EWS Watchlist]

Created attachment 349234 [details]
Archive of layout-test-results from ews102 for mac-sierra

The attached test failures were seen while running run-webkit-tests on the mac-ews.
Bot: ews102  Port: mac-sierra  Platform: Mac OS X 10.12.6

[EWS Watchlist]

Comment on attachment 349229 [details]
Fixes the bug

Attachment 349229 [details] did not pass mac-debug-ews (mac):
Output: https://webkit-queues.webkit.org/results/9136533

New failing tests:
fast/events/shadow-event-path.html

[EWS Watchlist]

Created attachment 349236 [details]
Archive of layout-test-results from ews116 for mac-sierra

The attached test failures were seen while running run-webkit-tests on the mac-debug-ews.
Bot: ews116  Port: mac-sierra  Platform: Mac OS X 10.12.6

[EWS Watchlist]

Comment on attachment 349229 [details]
Fixes the bug

Attachment 349229 [details] did not pass ios-sim-ews (ios-simulator-wk2):
Output: https://webkit-queues.webkit.org/results/9136558

New failing tests:
fast/shadow-dom/mouseenter-mouseleave-across-shadow-boundary.html
fast/shadow-dom/mouseenter-mouseleave-inside-shadow-tree.html
fast/shadow-dom/mouseenter-mouseleave-on-slot-parent.html

[EWS Watchlist]

Created attachment 349237 [details]
Archive of layout-test-results from ews125 for ios-simulator-wk2

The attached test failures were seen while running run-webkit-tests on the ios-sim-ews.
Bot: ews125  Port: ios-simulator-wk2  Platform: Mac OS X 10.13.4

[Ryosuke Niwa]

Created attachment 349242 [details]
Fixed tests

[Radar WebKit Bug Importer]

<rdar://problem/44251774>

[Ryosuke Niwa]

Thanks for the reviews!

[Ryosuke Niwa]

Committed r235865: <https://trac.webkit.org/changeset/235865>