src/vs/editor/contrib/hover/browser/marginHover.ts/MarginHoverWidget/_showAt
class MarginHoverWidget:	private _showAt(lineNumber: number): void {
		if (!this._isVisible) {
			this._isVisible = true;
			this._hover.containerDomNode.classList.toggle('hidden', !this._isVisible);
		}

		const editorLayout = this._editor.getLayoutInfo();
		const topForLineNumber = this._editor.getTopForLineNumber(lineNumber);
		const editorScrollTop = this._editor.getScrollTop();
		const lineHeight = this._editor.getOption(EditorOption.lineHeight);
		const nodeHeight = this._hover.containerDomNode.clientHeight;
		const top = topForLineNumber - editorScrollTop - ((nodeHeight - lineHeight) / 2);

		this._hover.containerDomNode.style.left = `${editorLayout.glyphMarginLeft + editorLayout.glyphMarginWidth}px`;
		this._hover.containerDomNode.style.top = `${Math.max(Math.round(top), 0)}px`;
	}