Hi 3am, thanks for your quick response.

Yes, I use the latest build.
Yes, I work on a copy in a desktop folder.
I tried to patch my theme files with UltraUXThemePatcher, but had no success after a reboot (not patched again). So I use SecureUxTheme, which signs the theme to be recognized by windows as valid (alternative recommendation by Manuel Hoefs, works fine).
The .theme file, .msstyle file and its folder are named by the theme name (e.g. there is no folder with .msstyles.mui to rename like in aero)

My problem in detail is described in the topic here (see red arrow):
https://www.vistastylebuilder.com/forum/index.php?topic=2542.0

Your suggestion: Windows 10 Dark Mode > Explorer & Shell > Shell > PreviewPaneControl > CommonItemsDialog:Edit > Background
has no effect (saving problem) PLUS my background in Windows is white, not light grey like in the image of your path.
In another style with another style editor the class "CommonItemsDialog" is responsible for changing this colour, that's why I want to add this class (have no clue). The properties there are:
BGTYPE: BORDERFILL,
BORDERSIZE: 0,
FILLCOLOR: R,G,B

Maybe I have to apply any specific stylehack or -script to update the classmap? But then saving style still is the problem.
Does perhaps the "Import 10 fix" have any impact on my problem?

Thanks for help and patience

Ups, double post.

Hi there,

I have a problem with my style builder (latest build).
I'm on Win10 21H2 and have a working style, patched with SecureUxTheme.
Each time I save a "before working" style, even if not modified, it doesn't work anymore, although Style Builder says that the file has been compiled successfully. Did I miss something?

If I understand right, patching with UltraUXThemePatcher is absolutely necessary for testing styles inside the software or starting from personalisation panel. But not for just modifying and saving styles, right?

I need to add a class to my style, but I can't save it.

Thanks and best wishes