Bug 164962 - Writer's horizontal scrollbar shows up randomly depending on window width, in "Fit Width" page zoom mode
Summary: Writer's horizontal scrollbar shows up randomly depending on window width, in...
Status: UNCONFIRMED
Alias: None
Product: LibreOffice
Classification: Unclassified
Component: Writer (show other bugs)
Version:
(earliest affected)
unspecified
Hardware: All Linux (All)
: medium normal
Assignee: Not Assigned
URL:
Whiteboard:
Keywords: perf
Depends on:
Blocks: Scrollbars Zoom Flickering-UI
  Show dependency treegraph
 
Reported: 2025-01-30 20:25 UTC by Jeff Fortin Tam
Modified: 2025-01-30 21:36 UTC (History)
0 users

See Also:
Crash report or crash signature:


Attachments
Demonstration video (931.20 KB, video/mp4)
2025-01-30 20:25 UTC, Jeff Fortin Tam
Details

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Description Jeff Fortin Tam 2025-01-30 20:25:44 UTC
Created attachment 198894 [details]
Demonstration video

See attached demonstration video.

1. Open Writer (it can be a blank document, or a document with contents)

2. Make sure page Zoom Factor is set to "Fit width". 
   Zoom's "View Layout" can be "Automatic" (i.e. single page) or "Columns: 2".

3. Slowly resize the width of the window

Result: the horizontal scrollbar frantically pops in and out of the view depending on the exact pixel position/width of the window.

This issue can also happen on startup / window creation, not just during resize.

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Tested on GNOME 47.2's Wayland session on Fedora 41, with:

Version: 24.8.4.2 (X86_64) / LibreOffice Community
Build ID: bb3cfa12c7b1bf994ecc5649a80400d06cd71002
CPU threads: 8; OS: Linux 6.12; UI render: default; VCL: gtk3
Locale: en-US (en_US.UTF-8); UI: en-US
Flatpak
Calc: threaded
Comment 1 Jeff Fortin Tam 2025-01-30 21:09:23 UTC
With my geek hat on, I'll also venture a guess that beyond the visual symptoms, this (and bug #164963) opens the potential for a performance optimization too:

If it's flashing the scrollbar like that, that means it's constantly calculating the width and checking whether it should be showing the scrollbar during resize. That is certainly very wasteful and contributes to unnecessary CPU usage, redraws, jank, etc.

If possible, don't make those checks at all when the zoom mode is set to automatically "Fit width" or "Fit width and height".