src/vs/editor/browser/widget/codeEditorWidget.ts/CodeEditorWidget/addOverlayWidget
class CodeEditorWidget:	public addOverlayWidget(widget: editorBrowser.IOverlayWidget): void {
		const widgetData: IOverlayWidgetData = {
			widget: widget,
			position: widget.getPosition()
		};

		if (this._overlayWidgets.hasOwnProperty(widget.getId())) {
			console.warn('Overwriting an overlay widget with the same id.');
		}

		this._overlayWidgets[widget.getId()] = widgetData;

		if (this._modelData && this._modelData.hasRealView) {
			this._modelData.view.addOverlayWidget(widgetData);
		}
	}