## Problem
When scrolling quickly, a distracting background color was appearing in
the scrollbar area, as shown below:
<img
src="https://github.com/user-attachments/assets/c9ebe200-a6b2-47ca-992d-ceaa5ed3db04">
## Root Cause
Several theme files had scrollbar background colors configured with
partial transparency (alpha values like `33`, `44`, `80`, etc.) instead
of full transparency (`00`). This caused a semi-transparent background
to become visible during fast scrolling, creating an unwanted visual
artifact.
## Solution
Updated all `scrollbar.background` color values to use full transparency
by setting the alpha channel to `00`. This ensures the scrollbar
background is completely invisible across all themes, with only the
scrollbar thumb (the draggable indicator) remaining visible.
## Changes
Modified 7 theme files with non-transparent scrollbar backgrounds:
- **alduin.json**: `#28282833` → `#28282800`
- **hybrid.json**: `#E0E0E044` → `#E0E0E000`, `#1D1F2144` → `#1D1F2100`
- **jellybeans.json**: `#26262633` → `#26262600`
- **mellifluous.json**: `#fafafa33` → `#fafafa00`
- **molokai.json**: `#FEFAF933` → `#FEFAF900`
- **solarized.json**: `#EEE8D533` → `#EEE8D500`, `#002b3633` →
`#002b3600`
- **default-theme.json**: `#fafafa80` → `#fafafa00`, `#17171780` →
`#17171700`
All other themes already had transparent scrollbar backgrounds and
remain unchanged.
## Impact
- Eliminates the visual glitch where a background color appears during
fast scrolling
- Provides a consistent, clean scrollbar appearance across all 20 themes
plus the default theme
- No functional changes to scrollbar behavior - only visual appearance
- Total of 37 scrollbar.background entries now fully transparent
Fixes the issue reported by @huacnlee in the comments.
<issue_title>A different background color appears when the scroll bar
scrolls quickly</issue_title>
><issue_description>A different background color appears when the
scroll bar scrolls quickly
>
><img
src="https://github.com/user-attachments/assets/c9ebe200-a6b2-47ca-992d-ceaa5ed3db04"></issue_description>
>
><agent_instructions>Make change to update scrollbar background color
to transparent for all themes.</agent_instructions>
>
> ## Comments on the Issue (you are @copilot in this section)
>
><comments>
><comment_new><author>@huacnlee</author>
> That is the scrollbar background color. I am still on to consider
removing that color.</comment_new>
></comments>
>
Fixeslongbridge/gpui-component#1402
<!-- START COPILOT CODING AGENT SUFFIX -->
<details>
<summary>Original prompt</summary>
>
> ----
>
> *This section details on the original issue you should resolve*
>
> <issue_title>A different background color appears when the scroll bar
scrolls quickly</issue_title>
> <issue_description>A different background color appears when the
scroll bar scrolls quickly
>
> <img width="1338" height="387" alt="Image"
src="https://github.com/user-attachments/assets/c9ebe200-a6b2-47ca-992d-ceaa5ed3db04"
/></issue_description>
>
> <agent_instructions>Make change to update scrollbar background color
to transparent for all themes.</agent_instructions>
>
> ## Comments on the Issue (you are @copilot in this section)
>
> <comments>
> <comment_new><author>@huacnlee</author><body>
> That is the scrollbar background color. I am still on to consider
removing that color.</body></comment_new>
> </comments>
>
</details>
Fixeslongbridge/gpui-component#1402
<!-- START COPILOT CODING AGENT TIPS -->
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Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: huacnlee <5518+huacnlee@users.noreply.github.com>
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