With devtools open: - I can trigger "Variant A" on-demand by adding+removing `display:none` on one of the outer divs (e.g. mx_MemberEventListSummary) - I can trigger "Variant B" on-demand by adding+removing `display:none` on the `<img>` element. So this seems like an inconsistency with full reflow (e.g. after forcing frames to be reconstructed for most of the page) vs. incremental reflow (e.g. after forcing frames to be reconstructed for the `<img>`), and the image-load is what's triggering the race condition that gives us one or the other behavior.
Bug 1535053 Comment 3 Edit History
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With devtools open: - I can trigger "Variant A" on-demand by adding+removing `display:none` on one of the outer divs (e.g. `<div class="mx_MemberEventListSummary">`) - I can trigger "Variant B" on-demand by adding+removing `display:none` on the `<img>` element. So this seems like an inconsistency with full reflow (e.g. after forcing frames to be reconstructed for most of the page) vs. incremental reflow (e.g. after forcing frames to be reconstructed for the `<img>`), and the image-load is what's triggering the race condition that gives us one or the other behavior.
With devtools open: - I can trigger "Variant A" on-demand by adding+removing `display:none` on one of the outer divs (e.g. `<div class="mx_MemberEventListSummary">`) - I can trigger "Variant B" on-demand by adding+removing `display:none` on the `<img>` element. So this seems like an inconsistency with full reflow (e.g. after forcing frames to be reconstructed for most of the page) vs. incremental reflow (e.g. after forcing frames to be reconstructed for the `<img>`). And in jryans's STR, it's likely the image-load [and its resulting incremental reflow] that is triggering the race condition that gives us one or the other behavior.