src/vs/workbench/contrib/notebook/browser/viewParts/notebookOverviewRuler.ts/NotebookOverviewRuler/layout
class NotebookOverviewRuler:	layout() {
		const width = 10;
		const layoutInfo = this.notebookEditor.getLayoutInfo();
		const scrollHeight = layoutInfo.scrollHeight;
		const height = layoutInfo.height;
		const ratio = browser.PixelRatio.value;
		this._domNode.setWidth(width);
		this._domNode.setHeight(height);
		this._domNode.domNode.width = width * ratio;
		this._domNode.domNode.height = height * ratio;
		const ctx = this._domNode.domNode.getContext('2d')!;
		ctx.clearRect(0, 0, width * ratio, height * ratio);
		this._render(ctx, width * ratio, height * ratio, scrollHeight * ratio, ratio);
	}