tor-browser

commit f2dc3d6423d33cc4162c326e1dd424a312a06372
parent 47d67ca923c5881cb8dd6e58a8202e93b5381804
Author: David Shin <dshin@mozilla.com>
Date:   Fri, 28 Nov 2025 19:46:06 +0000

Bug 1999954: Explicitly schedule a paint for scroll-compensated anchor-positioned frames. r=jwatt

Differential Revision: https://phabricator.services.mozilla.com/D274348

Diffstat:
M
layout/base/PresShell.cpp
 | 
7
+++++++

1 file changed, 7 insertions(+), 0 deletions(-)
diff --git a/layout/base/PresShell.cpp b/layout/base/PresShell.cpp
@@ -11733,6 +11733,13 @@ void PresShell::UpdateAnchorPosForScroll(
       // block's.
       positioned->UpdateOverflow();
       positioned->GetParent()->UpdateOverflow();
+      // APZ-handled scrolling may skip scheduling of paint for the relevant
+      // scroll container - We need to ensure that we schedule a paint for this
+      // positioned frame. Could theoretically do this when deciding to skip
+      // painting in `ScrollContainerFrame::ScrollToImpl`, that'd be conditional
+      // on finding a dependent anchor anyway, we should be as specific as
+      // possible as to what gets scheduled to paint.
+      positioned->SchedulePaint();
       referenceData->mDefaultScrollShift = offset;
       return true;
     }();