930463 - Overinvalidation of devtools' "inspect element"-selected element, when scrolling & when arrow-label is below the inspected element

Status: NEW

(Core :: Layout, defect)

Description

[Daniel Holbert [:dholbert]]

Attachment: testcase 1

STR:
 0. Enable paint flashing.
 1. Open attached testcase.
 2. Right-click the black-bordered region and pick "Inspect Element"
 3. Scroll the page.

ACTUAL RESULTS: The full black-bordered region is invalidated with each scroll-tick.

Comment 1

[Daniel Holbert [:dholbert]]

Attachment: screencast (overinvalidation happens towards the end, when "div" label jumps to bottom)

Here's a screencast of the STR on testcase 1, with a small Firefox window.

As shown here, the over-invalidation actually *only* happens after the devtools label is bumped down to below the element. (which happens as soon as the bottom of the element is visible (i.e. right away if the element is shorter than your browser-window))

So it looks like this is being caused by that label somehow.