1883550 - Avoid triggering synchronous reflow in when calculating TreeView's visible height

Status: RESOLVED FIXED

(Thunderbird :: Folder and Message Lists, enhancement)

Description

[Geoff Lankow (:darktrojan)]

TreeView.#calculateVisibleHeight can cause synchronous reflow to get the table's height. But it doesn't need to – we already know the table's height because we have a ResizeObserver watching it. If we just remember the height from the last time it changed¹, we can avoid this function being the cause of a reflow and blame something else for it.

(¹ …and the height of the table header, which we can watch in a similar way.)

Comment 1

[Geoff Lankow (:darktrojan)]

Attachment: Bug 1883550 - Avoid triggering synchronous reflow in when calculating TreeView's visible height. r=leftmostcat

Comment 2

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/comm-central/rev/89a8fa3b520f
Avoid triggering synchronous reflow in when calculating TreeView's visible height. r=leftmostcat

Comment 3

[Geoff Lankow (:darktrojan)]

Comment on attachment 9389277 [details]
Bug 1883550 - Avoid triggering synchronous reflow in when calculating TreeView's visible height. r=leftmostcat

[Approval Request Comment]
Regression caused by (bug #): Message list performance improvement in some circumstances. Potentially fixes bug 1860094.
User impact if declined:
Testing completed (on c-c, etc.): In 125 beta 1.
Risk to taking this patch (and alternatives if risky): Low.

Comment 4

[Geoff Lankow (:darktrojan)]

Comment on attachment 9389277 [details]
Bug 1883550 - Avoid triggering synchronous reflow in when calculating TreeView's visible height. r=leftmostcat

Flag went missing. User error. :-)

Comment 5

[Wayne Mery (:wsmwk)]

Comment on attachment 9389277 [details]
Bug 1883550 - Avoid triggering synchronous reflow in when calculating TreeView's visible height. r=leftmostcat

[Triage Comment]
Approved for esr115

Comment 6

[Rob Lemley [:rjl]]

Thunderbird 115.10.0:
https://hg.mozilla.org/releases/comm-esr115/rev/459b6d2a94d1