Bug 402285 - Scrolling not smooth when using native scrollbars
Summary: Scrolling not smooth when using native scrollbars
Status: RESOLVED WORKSFORME
Alias: None
Product: Falkon
Classification: Applications
Component: general (show other bugs)
Version: unspecified
Platform: Other Linux
: NOR normal
Target Milestone: ---
Assignee: David Rosca
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2018-12-18 09:18 UTC by tromzy
Modified: 2020-11-24 04:34 UTC (History)
2 users (show)

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Latest Commit:
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Description tromzy 2018-12-18 09:18:25 UTC
SUMMARY
With animated scrolling enabled, if I check "Use native scrollbars" in Falkon settings, scrolling webpages is jerky. If I uncheck it, scrolling is butter smooth again. I'm using Falkon on a Wayland session, I did not try on X.org.

STEPS TO REPRODUCE
1. (Use Wayland) Check "Use native scrollbars" in Falkon preferences, check also "Animated scrolling"
2. Restart Falkon to make the change take effect
3. Scroll any webpage

OBSERVED RESULT
The scrolling is not smooth at all, it's choppy.

EXPECTED RESULT
Scrolling should be as smooth as when not using native scrollbars.

SOFTWARE/OS VERSIONS
Windows: 
MacOS: 
Linux/KDE Plasma: 
(available in About System)
KDE Plasma Version: 5.14.4
KDE Frameworks Version: 5.53
Qt Version: 5.12

ADDITIONAL INFORMATION
Using latest Falkon-git.
Comment 1 Alexander Browne 2018-12-18 14:07:07 UTC
This is a known issue that was discussed on Github back when Falkon was Qupzilla: <https://github.com/QupZilla/qupzilla/issues/2246>. The issue is still present with animated scrolling disabled, it's just less noticeable.

The best workaround I've found is to disable the native scrollbar feature and style the Chromium scrollbars with a user style sheet. I take the CSS from the Plasma Browser Integration[1] (lines 94–130): https://cgit.kde.org/plasma-browser-integration.git/tree/extension/content-script.js#n94 

One caveat I've noticed is that CSS scrollbars like this scale with the page zoom.

1: https://community.kde.org/Plasma/Browser_Integration
Comment 2 tromzy 2018-12-18 14:23:15 UTC
Thank you for your answer. Where is the CSS file I should modify ? Is it in .config/falkon.profiles/default ? I can't seem to find it.
Comment 3 Alexander Browne 2018-12-18 14:42:53 UTC
The CSS file itself can be saved anywhere I think, and then you can choose it in Preferences → Other (at the very bottom) → User Style Sheet.
Comment 4 tromzy 2018-12-18 14:45:58 UTC
Thanks, it works !
Comment 5 David Rosca 2018-12-24 12:06:42 UTC
This is the reason why they are disabled by default, and most likely will be removed from future releases as there doesn't seem to be way to make it work without this performance hit.
Comment 6 Justin Zobel 2020-10-25 04:30:02 UTC
I've just tried this on Wayland on Falkon 3.1.0 and with both settings on it's still very smooth. Can you please retest and confirm if this is still an issue, thanks.
Comment 7 Bug Janitor Service 2020-11-09 04:33:52 UTC
Dear Bug Submitter,

This bug has been in NEEDSINFO status with no change for at least
15 days. Please provide the requested information as soon as
possible and set the bug status as REPORTED. Due to regular bug
tracker maintenance, if the bug is still in NEEDSINFO status with
no change in 30 days the bug will be closed as RESOLVED > WORKSFORME
due to lack of needed information.

For more information about our bug triaging procedures please read the
wiki located here:
https://community.kde.org/Guidelines_and_HOWTOs/Bug_triaging

If you have already provided the requested information, please
mark the bug as REPORTED so that the KDE team knows that the bug is
ready to be confirmed.

Thank you for helping us make KDE software even better for everyone!
Comment 8 Bug Janitor Service 2020-11-24 04:34:16 UTC
This bug has been in NEEDSINFO status with no change for at least
30 days. The bug is now closed as RESOLVED > WORKSFORME
due to lack of needed information.

For more information about our bug triaging procedures please read the
wiki located here:
https://community.kde.org/Guidelines_and_HOWTOs/Bug_triaging

Thank you for helping us make KDE software even better for everyone!