foldBackground needs transparency. Fixes #91034

src/vs/editor/contrib/folding/folding.ts

@@ -885,7 +885,7 @@ for (let i = 1; i <= 7; i++) {
 	);
 }
 
-export const foldBackgroundBackground = registerColor('editor.foldBackground', { light: transparent(editorSelectionBackground, 0.3), dark: transparent(editorSelectionBackground, 0.3), hc: null }, nls.localize('foldBackgroundBackground', "Background color behind folded ranges."));
+export const foldBackgroundBackground = registerColor('editor.foldBackground', { light: transparent(editorSelectionBackground, 0.3), dark: transparent(editorSelectionBackground, 0.3), hc: null }, nls.localize('foldBackgroundBackground', "Background color behind folded ranges. The color must not be opaque so as not to hide underlying decorations."), true);
 
 registerThemingParticipant((theme, collector) => {
 	const foldBackground = theme.getColor(foldBackgroundBackground);