Closed Bug 1666792 Opened 4 years ago Closed 3 years ago

Not able to select first option in the location dropdown of StackOverflow's job application page in Desktop Site mode


(Core :: Panning and Zooming, defect, P3)




83 Branch
Tracking Status
firefox-esr78 --- unaffected
firefox81 --- wontfix
firefox82 --- wontfix
firefox83 --- fixed


(Reporter: amejia, Assigned: kats)




(Keywords: regression)


(1 file)

Steps to reproduce in the Fenix issue. Reproducible in GV: 82.0a1-20200920213416 and in GVE app.

Component: General → Panning and Zooming
Product: GeckoView → Core

I got a regression window with GVE. It points to:

Bug 1618532 - Re-enable mouse event retargeting on Android

Regressed by: 1618532
Has Regression Range: --- → yes
Assignee: nobody → kats
Severity: -- → S3
Priority: -- → P3

Looks like there's nothing on the dropdown list elements that makes them mouse targets. The first item in the list is close enough to the input box that any attempts to tap on it just get retargeted to the input box.

Inspecting the dropdown elements in Chrome (after removing the blur listener on the input element, which apparently I can't do in Firefox) shows almost nothing interesting about the elements except a mousemove listener. So maybe we can use that. All the actual important click listeners are on the html or body elements.

Another option is that the pac-container parent element has a z-index:9999 which is kind of a signal that it's important and mouse events should not get retargeted to outside it. So maybe we can restrict the retarget to be inside frames with sufficiently high z-index.

I think the z-index idea is probably the one worth going with here, but I'm not sure how z-index is used in practice. It seems like it would be used for things like web modal dialogs and popup implementations, where it makes sense that we probably don't want to retarget events that land on the z-island to things outside of it. I wrote a patch that does this and it seems to work in this case. Not sure if it is too conservative and will disable retargeting in a lot of scenarios where it's useful, but I guess we can see.

Pushed by
Don't allow events to get retargeted outside the nearest z-index container. r=emilio
Closed: 3 years ago
Resolution: --- → FIXED
Target Milestone: --- → 83 Branch

Verified as fixed on Firefox Preview Nightly 201025 (Build #2015771787) using a Pixel 3 XL (Android 9) and Samsung Galaxy S9 (Android 8.0.0).

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