Fixes #85531: Support overviewRulerLanes = 0

src/vs/base/browser/fastDomNode.ts

@@ -25,6 +25,7 @@ export class FastDomNode<T extends HTMLElement> {
 	private _display: string;
 	private _position: string;
 	private _visibility: string;
+	private _backgroundColor: string;
 	private _layerHint: boolean;
 	private _contain: 'none' | 'strict' | 'content' | 'size' | 'layout' | 'style' | 'paint';
 
@@ -47,6 +48,7 @@ export class FastDomNode<T extends HTMLElement> {
 		this._display = '';
 		this._position = '';
 		this._visibility = '';
+		this._backgroundColor = '';
 		this._layerHint = false;
 		this._contain = 'none';
 	}
@@ -200,6 +202,14 @@ export class FastDomNode<T extends HTMLElement> {
 		this.domNode.style.visibility = this._visibility;
 	}
 
+	public setBackgroundColor(backgroundColor: string): void {
+		if (this._backgroundColor === backgroundColor) {
+			return;
+		}
+		this._backgroundColor = backgroundColor;
+		this.domNode.style.backgroundColor = this._backgroundColor;
+	}
+
 	public setLayerHinting(layerHint: boolean): void {
 		if (this._layerHint === layerHint) {
 			return;

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

@@ -74,8 +74,14 @@ class Settings {
 		this.right = position.right;
 		this.domWidth = position.width;
 		this.domHeight = position.height;
-		this.canvasWidth = (this.domWidth * this.pixelRatio) | 0;
-		this.canvasHeight = (this.domHeight * this.pixelRatio) | 0;
+		if (this.overviewRulerLanes === 0) {
+			// overview ruler is off
+			this.canvasWidth = 0;
+			this.canvasHeight = 0;
+		} else {
+			this.canvasWidth = (this.domWidth * this.pixelRatio) | 0;
+			this.canvasHeight = (this.domHeight * this.pixelRatio) | 0;
+		}
 
 		const [x, w] = this._initLanes(1, this.canvasWidth, this.overviewRulerLanes);
 		this.x = x;
@@ -303,6 +309,11 @@ export class DecorationsOverviewRuler extends ViewPart {
 	}
 
 	private _render(): void {
+		if (this._settings.overviewRulerLanes === 0) {
+			// overview ruler is off
+			this._domNode.setBackgroundColor(this._settings.backgroundColor ? this._settings.backgroundColor : '');
+			return;
+		}
 		const canvasWidth = this._settings.canvasWidth;
 		const canvasHeight = this._settings.canvasHeight;
 		const lineHeight = this._settings.lineHeight;