some color scheme options wont work

Hello p851 ,

I tried to reproduce the issue, but I was not able to do so, or I may not have understood to which options you are referring. I tried changing the Background of scrollBar at Settings | Editor | Color Scheme | General → Editor | Vertical Scrollbar | Thumb and it applies the changes as expected:

If you, instead, are referring to the color picker not changing when using the slider, then I was able to reproduce the problem:

I opened a new bug to track this problem. Please subscribe to IDEA-390223 to get future updates and upvote so we can see the real number of affected users. Meanwhile, this is fixed. As a workaround, you can select the drop selector and choose a color in the slider. After that, you'll be able to change the color directly by sliding:

Regarding Errors and Warnings | Unused code | Error stripe mark it's working as expected for me, I can see the error stripes on unused lines:

If you can't see the stripe working in the Code Inspection example panel, it's because the stripes are not moving along with the code, which is a usability problem I'm registering. If what you need is an extra decoration on the text itself in the editor: underline, wavy underline, box, strikethrough, etc., then you can use the Effect option (Effects dropdown + Effects color), and you will see it directly on the code line.

hi Monica

for me it just wont color the scrollbars
also ive noticed that the scrollbar thumbs on your screenshots have rounded corners while i have them sharp, maybe its related to it (?)

also ive noticed that in the ui inspecting tool (the ctrl+alt click thing) the colors of the scrollbar are set to colors from the theme and not my custom color scheme (idk if this is important but i found it funny)

as for the error stripe marks - they only show correctly in the preview textbox for whatever reason (also ive checked kotlin specific color schemes but i couldnt find an unused symbol/code style)

(also idk how i didnt think of adding screenshots when i posted this)

Hi p851 

Thanks for the details and screenshots; they're very helpful. I was able to reproduce the issue halfway. Please check the steps and let me know if it works differently for you. Add the missing steps or remove them depending on the situation:

1. Installed the same theme plugin, Iceberg.
2. Modified the same options you mentioned, and click Apply.
3. The color of the error stripe doesn't match between the sample code block and the Editor, but once OK is clicked, the change is made in the Editor as well.

Also, please share the next:

1. Verify the IDE version (I'm running 2026.1.3). Go to Help | About, click Copy, and paste the text here.
2. Verify using the default theme and modifying the options to check if that works.
3. If you have any other theme plugins that might be interfering with this one, disable them and test again just with Iceberg active.
4. If the previous doesn't work, then disable all custom plugins. Go to Settings | Plugins | ⚙ | Disable all downloaded plugins, and click the OK button. Verify if the issue persists. If it's resolved, then start enabling the plugins one by one to find the problematic one.

If nothing works, please share the steps you followed or a simple sample of the custom color scheme you created so I can try to reproduce the problem on my end.

hi Monica 

the info from help \ about:
IntelliJ IDEA 2026.1.3
Build #IU-261.25134.95, built on June 3, 2026
Source revision: adfd17059a568
Runtime version: 25.0.3+1-b329.124 amd64137.0.17-261-b86
VM: OpenJDK 64-Bit Server VM by JetBrains s.r.o.
Toolkit: sun.awt.windows.WToolkit
Windows 11.0
Exception reporter ID: 250525127ac32fb-4bc1-4ca5-a79a-cc2be305c68e
Kotlin analyzer version: 2.4.0-ij261-64
GC: G1 Young Generation, G1 Concurrent GC, G1 Old Generation
Memory: 2048M
Cores: 12
Registry:
 ide.experimental.ui=true
 editor.ux.survey.enabled=false
 trace.state.event.service.url=https://api.jetbrains.cloud/trace-status
Non-Bundled Plugins:
 org.jetbrains.completion.full.line (261.25134.95)
 com.github.milankinen.ideaicebergtheme (0.7.0)
 DevKit (261.25134.67)
 com.demonwav.minecraft-dev (2026.1-1.8.17)
Kotlin: 261.25134.95-IJ

and as i was about to post this i was messing around with settings and turned on “Enable Islands UI for custom themes” which fixed the scrollbars (im assuming some of the color scheme settings are only implemented for islands ui) however it only uses the “Thumb while scrolling” color in the preview textbox (also in the preview textbox if you move your mouse outside the textbox the scrollbar becomes a lot wider for some reason)

also ive found out that the error stripe mark for unused code gets overriden by the warning error stripe mark - when i remove the warning error stripe mark the unused one will show (theyre most likely stacked on top of each other or the warning one takes priority however im unsure how to resolve this)

Hello @p851

Thanks for the specifications and tests you did. I was able to reproduce the Thumb color issues and routed it to the right ticket, IJPL-58798. Please subscribe for further updates and upvote so we can see the real number of affected users.

Regarding the other issues you mentioned, I'm still unable to reproduce them on my end. Error stripes are colored and visible as expected. Did you try changing the Error stripe color and, after clicking Apply and OK, reopening the file in the Editor where you have the unused code symbol, to reload the UI?

About the “Enable Islands UI for custom themes” option, it is not exactly related to the problem; what it really does and is designed for is to route Windows + Iceberg through the newer Islands scrollbar implementation (you're forcing Mac scrollbars), which currently sidesteps the Windows scrollbar bugs you’ve hit, but this setting is designed for older custom themes that still inherit from legacy Dark/Light/Darcula.

So, the proper workaround in your case would be disabling the scrollbar transparency in the registry:

1. Open IDE Registry (Ctrl+Shift+A, type "Registry"),
2. In the appearing window, start typing editor.transparent.scrollbar,
3. Uncheck the corresponding key,
4. Restart the IDE.

This will apply the colors, keeping Windows scrollbars. It looks like you need to hover the mouse over the scrollbar for the scrolling color.

yep that fixed the scrollbars
and ive also finally figured out what the issue with the error stripes was - kotlin uses different styles for different unused code (variables, expressions, …)
so under Editor \ Inspections \ Kotlin \ … i just changed the different styles used for the unused things

Hi p851 

Thanks for sharing that suggestion worked. It's good to hear that the styles are looking as expected now.

Have a great day ahead!