1489329 - flexbox / grid overlays can be scrolled offscreen independently from their content, e.g. for fixed-position grid/flex container that remains onscreen

Status: RESOLVED DUPLICATE of bug 1521067

(DevTools :: Inspector, defect, P3)

Description

[Daniel Holbert [:dholbert]]

Attachment: test.html

STR:
 1. View attached testcase.
 2. Activate grid inspector or flex overlay
   (click the badge next to the element in the Inspector view)
 3. Scroll the page.

ACTUAL RESULTS:
The overlays scroll offscreen, even though the grid & flex containers remain onscreen (since they're fixed-position).

EXPECTED RESULTS:
The overlays should remain over the elements that they're trying to overlay.


Note: I ran into this in the wild when trying to use the flexbox inspector on the toolbar at the very top of https://new.reddit.com (with "Search Reddit", "Log In", etc.)  If you activate the overlay for any of the flex containers inside that overlay, the overlay will be scrolled offscreen when you start to scroll the page.  (Or, kinda-worse: if you've already scrolled down a bit and *then* you try to activate the overlay on that toolbar, then you simply never see it at all, because it appears somewhere off the top of your screen.)

Comment 1

[Daniel Holbert [:dholbert]]

FWIW I just ran into this in the wild when inspecting the (fixed-position) header at https://www.nytimes.com/subscription/ .

(Especially broken-feeling: if you scroll down first, and then activate the overlay by e.g. clicking on the flex badge in Inspector, then you never see the overlay and it just feels broken.)

Comment 2

[Daniel Holbert [:dholbert]]

Looks like we also recently filed bug 1521026 and bug 1521067 to cover this. (for flex & grid overlays, respectively)

I'll dupe this to the latter (the one that's still open).