fix #111886.

src/vs/workbench/contrib/notebook/browser/notebookEditorWidget.ts

@@ -2587,6 +2587,7 @@ export class NotebookEditorWidget extends Disposable implements INotebookEditor
 	setMarkupCellEditState(cellId: string, editState: CellEditState): void {
 		const cell = this.getCellById(cellId);
 		if (cell instanceof MarkupCellViewModel) {
+			this.revealInView(cell);
 			cell.updateEditState(editState, 'setMarkdownCellEditState');
 		}
 	}

src/vs/workbench/contrib/notebook/browser/view/notebookCellList.ts

@@ -182,6 +182,8 @@ export class NotebookCellList extends WorkbenchList<CellViewModel> implements ID
 			const focus = this.getFocusedElements()[0];
 
 			if (focus && focus.cellKind === CellKind.Markup && !focus.metadata.inputCollapsed && !this._viewModel?.options.isReadOnly) {
+				// scroll the cell into view if out of viewport
+				this.revealElementInView(focus);
 				focus.updateEditState(CellEditState.Editing, 'dbclick');
 				focus.focusMode = CellFocusMode.Editor;
 			}