src/vs/workbench/contrib/notebook/browser/notebookEditorWidget.ts/NotebookEditorWidget/_didStartDragMarkupCell
class NotebookEditorWidget:	private _didStartDragMarkupCell(cellId: string, event: { dragOffsetY: number }): void {
		const cell = this._getCellById(cellId);
		if (cell instanceof MarkupCellViewModel) {
			const webviewOffset = this._list.webviewElement ? -parseInt(this._list.webviewElement.domNode.style.top, 10) : 0;
			this._dndController?.startExplicitDrag(cell, event.dragOffsetY - webviewOffset);
		}
	}