Fixes #84565: Mark all editor layers as strictly contained (have the layers always pass the opacity check)

src/vs/base/browser/fastDomNode.ts

@@ -26,6 +26,7 @@ export class FastDomNode<T extends HTMLElement> {
 	private _position: string;
 	private _visibility: string;
 	private _layerHint: boolean;
+	private _contain: 'none' | 'strict' | 'content' | 'size' | 'layout' | 'style' | 'paint';
 
 	constructor(domNode: T) {
 		this.domNode = domNode;
@@ -47,6 +48,7 @@ export class FastDomNode<T extends HTMLElement> {
 		this._position = '';
 		this._visibility = '';
 		this._layerHint = false;
+		this._contain = 'none';
 	}
 
 	public setMaxWidth(maxWidth: number): void {
@@ -206,6 +208,14 @@ export class FastDomNode<T extends HTMLElement> {
 		(<any>this.domNode.style).willChange = this._layerHint ? 'transform' : 'auto';
 	}
 
+	public setContain(contain: 'none' | 'strict' | 'content' | 'size' | 'layout' | 'style' | 'paint'): void {
+		if (this._contain === contain) {
+			return;
+		}
+		this._contain = contain;
+		(<any>this.domNode.style).contain = this._contain;
+	}
+
 	public setAttribute(name: string, value: string): void {
 		this.domNode.setAttribute(name, value);
 	}

src/vs/base/browser/ui/scrollbar/abstractScrollbar.ts

@@ -99,6 +99,7 @@ export abstract class AbstractScrollbar extends Widget {
 			this.slider.setHeight(height);
 		}
 		this.slider.setLayerHinting(true);
+		this.slider.setContain('strict');
 
 		this.domNode.domNode.appendChild(this.slider.domNode);
 

src/vs/editor/browser/viewParts/lines/viewLines.ts

@@ -544,6 +544,7 @@ export class ViewLines extends ViewPart implements IVisibleLinesHost<ViewLine>,
 
 		// (3) handle scrolling
 		this._linesContent.setLayerHinting(this._canUseLayerHinting);
+		this._linesContent.setContain('strict');
 		const adjustedScrollTop = this._context.viewLayout.getCurrentScrollTop() - viewportData.bigNumbersDelta;
 		this._linesContent.setTop(-adjustedScrollTop);
 		this._linesContent.setLeft(-this._context.viewLayout.getCurrentScrollLeft());

src/vs/editor/browser/viewParts/margin/margin.ts

@@ -78,6 +78,7 @@ export class Margin extends ViewPart {
 
 	public render(ctx: RestrictedRenderingContext): void {
 		this._domNode.setLayerHinting(this._canUseLayerHinting);
+		this._domNode.setContain('strict');
 		const adjustedScrollTop = ctx.scrollTop - ctx.bigNumbersDelta;
 		this._domNode.setTop(-adjustedScrollTop);
 

src/vs/editor/browser/viewParts/minimap/minimap.ts

@@ -503,6 +503,7 @@ export class Minimap extends ViewPart {
 		this._slider.setPosition('absolute');
 		this._slider.setClassName('minimap-slider');
 		this._slider.setLayerHinting(true);
+		this._slider.setContain('strict');
 		this._domNode.appendChild(this._slider);
 
 		this._sliderHorizontal = createFastDomNode(document.createElement('div'));

src/vs/editor/browser/viewParts/overviewRuler/decorationsOverviewRuler.ts

@@ -215,6 +215,7 @@ export class DecorationsOverviewRuler extends ViewPart {
 		this._domNode.setClassName('decorationsOverviewRuler');
 		this._domNode.setPosition('absolute');
 		this._domNode.setLayerHinting(true);
+		this._domNode.setContain('strict');
 		this._domNode.setAttribute('aria-hidden', 'true');
 
 		this._updateSettings(false);

src/vs/editor/browser/viewParts/overviewRuler/overviewRuler.ts

@@ -26,6 +26,7 @@ export class OverviewRuler extends ViewEventHandler implements IOverviewRuler {
 		this._domNode.setClassName(cssClassName);
 		this._domNode.setPosition('absolute');
 		this._domNode.setLayerHinting(true);
+		this._domNode.setContain('strict');
 
 		this._zoneManager = new OverviewZoneManager((lineNumber: number) => this._context.viewLayout.getVerticalOffsetForLineNumber(lineNumber));
 		this._zoneManager.setDOMWidth(0);