src/vs/workbench/contrib/notebook/browser/view/cellParts/cellDragRenderer.ts/CodeCellDragImageRenderer/getDragImageImpl
class CodeCellDragImageRenderer:	private getDragImageImpl(templateData: BaseCellRenderTemplate, editor: ICodeEditor, type: 'code' | 'markdown'): HTMLElement | null {
		const dragImageContainer = templateData.container.cloneNode(true) as HTMLElement;
		dragImageContainer.classList.forEach(c => dragImageContainer.classList.remove(c));
		dragImageContainer.classList.add('cell-drag-image', 'monaco-list-row', 'focused', `${type}-cell-row`);

		const editorContainer: HTMLElement | null = dragImageContainer.querySelector('.cell-editor-container');
		if (!editorContainer) {
			return null;
		}

		const richEditorText = new EditorTextRenderer().getRichText(editor, new Range(1, 1, 1, 1000));
		if (!richEditorText) {
			return null;
		}
		DOM.reset(editorContainer, richEditorText);

		return dragImageContainer;
	}