<select> dropdown can appear in the wrong position when inside a container with position:sticky

NEW
Unassigned

Status

()

Core
Layout
3 years ago
2 years ago

People

(Reporter: MattN, Unassigned)

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Firefox Tracking Flags

(Not tracked)

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(URL)

Attachments

(2 attachments)

Created attachment 8562613 [details]
Testcase (scroll while the dropdown is open)

I regularly see the <select> dropdown in the wrong position on my bug dependency tree dashboard. I'm not sure of all of the possible ways to reproduce the issue but scrolling upwards while a <select> dropdown popup is open seems to trigger it. Once it's in the wrong position, it will remain in that wrong position upon reopening too. Click and keyboard behaviour becomes wonky when the popup is in the wrong position.
Attachment #8562613 - Attachment filename: file_1131944.txt → file_1131944.htm
Attachment #8562613 - Attachment mime type: text/plain → text/html
Created attachment 8562617 [details]
Video showing a mild version of the problem using the testcase

This shows a mild version of the problem using my testcase. On my bug dashboard I regularly see the dropdown vertical position off by multiple centimetres.
Duplicate of this bug: 1199991
I wonder if this could be a case of a missing MovePositionBy. See bug 911786 comment 12 to 17. Although the <select> itself doesn't need to be position: sticky to show the problem.
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