src/vs/editor/browser/widget/codeEditorWidget.ts/CodeEditorWidget/setBanner
class CodeEditorWidget:	public setBanner(domNode: HTMLElement | null, domNodeHeight: number): void {
		if (this._bannerDomNode && this._domElement.contains(this._bannerDomNode)) {
			this._domElement.removeChild(this._bannerDomNode);
		}

		this._bannerDomNode = domNode;
		this._configuration.setReservedHeight(domNode ? domNodeHeight : 0);

		if (this._bannerDomNode) {
			this._domElement.prepend(this._bannerDomNode);
		}
	}