1521825 - Flex highlighter doesn't redraw in correct position for position:fixed elements whose fixedpos CB isn't the viewport

Status: NEW

(DevTools :: Inspector, defect, P2)

Description

[Daniel Holbert [:dholbert] (PTO until 2/24)]

Attachment: testcase 1

STR:

1. Load attached testcase.
2. Activate the flex highlighter overlay for the fixed-pos flex container.
3. Scroll all the way to the bottom of the page.
4. Scroll all the way back to the top of the page.

EXPECTED RESULTS:
Overlay should still be on the flex container when you get back to the top.

ACTUAL RESULTS:
Overlay isn't positioned correctly at the end of STR (and may not even be visible). If you scroll up slowly, you can see it redrawing at one or two seemingly-arbitrary incorrect positions on the way up.

I think this is a regression from bug 1521026 -- that bug added a special case for fixedpos elements, but this bug here is about an extra-special case: fixedpos elements whose fixed-pos containing block is something other than the viewport, due to having e.g. 'transform' or 'filter' set on some ancestor (or will-change:[either of those properties]).

Comment 1

[Daniel Holbert [:dholbert] (PTO until 2/24)]

Attachment: screencast of bug

Comment 2

[Gabriel Luong [:gl] (ΦωΦ)]

Mike, can you take a look?

Comment 3

[Mike Ratcliffe [:miker] [:mratcliffe] [:mikeratcliffe]]

I will add it to my list.