https://bugs.documentfoundation.org/show_bug.cgi?id=173112
Bug ID: 173112
Summary: Intermittent 9–45 second UI hang/beach ball when
interacting with vertical scrollbar in Writer on macOS
26.6.1
Product: LibreOffice
Version: 26.2.4.2 release
Hardware: ARM
OS: macOS (All)
Status: UNCONFIRMED
Severity: normal
Priority: medium
Component: Writer
Assignee: [email protected]
Reporter: [email protected]
Description:
LibreOffice Writer intermittently becomes unresponsive and displays the macOS
spinning beach ball when I interact directly with the vertical scrollbar.
The hang can occur when dragging the scrollbar thumb and has also occurred when
clicking in the scrollbar track above or below the thumb.
The freezes are intermittent rather than occurring on every scrollbar
interaction. Observed hangs have ranged from approximately 9 seconds to 44
seconds, after which Writer becomes responsive again without crashing.
Avoiding direct interaction with the scrollbar appears to avoid the problem.
Steps to Reproduce:
1. Open a document in LibreOffice Writer.
2. Work in the document normally.
3. Interact with the vertical scrollbar by dragging the scrollbar thumb or
clicking in the scrollbar track.
4. Repeat during normal use.
The problem is intermittent, so it may take multiple scrollbar interactions
before it occurs.
Actual Results:
Writer intermittently becomes unresponsive and macOS displays the spinning
beach ball. The hang can last approximately 9–45 seconds before Writer resumes
responding normally.
Interestingly, switching focus away from LibreOffice appears to cause the beach
ball/hang to end.
Expected Results:
Dragging or clicking the vertical scrollbar should scroll the document without
causing Writer to become unresponsive.
Reproducible: Sometimes
User Profile Reset: Yes
Additional Info:
Troubleshooting already performed:
* Problem occurred in LibreOffice 26.2.4.2.
* Updated to LibreOffice 26.2.5.2; problem persists.
* Tested with normal Skia/Metal rendering.
* Tested with Skia/Raster using SAL_DISABLESKIA=1; problem persists.
* Tested LibreOffice Safe Mode; problem persists.
* Therefore the problem does not appear to be caused by the normal user
profile, extensions, or Skia/Metal rendering.
* When direct scrollbar interaction was deliberately avoided during an extended
work session, no hangs occurred.
Process sampling:
A continuous macOS sample capture was run while using Writer so that
diagnostics could be collected without switching focus away from LibreOffice
during a hang.
During a scrollbar-related incident, the main thread was captured processing a
mouse drag through LibreOffice’s scrollbar/native-control drawing path,
including functions such as:
mouseDraggedWithTimer
ScrollBar::Tracking
ScrollBar::ImplDragThumb
ScrollBar::ImplDrawNative
AquaSalGraphics::drawNativeControl
The stack then proceeds into macOS AppKit/Quartz native drawing code.
Samples immediately outside the problematic interaction show the LibreOffice
main thread normally waiting in the macOS event loop.
I can attach the complete continuous sampling log
(LibreOffice-Watch-20260811-184818.txt) to this report.
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