fix #104196. detached overflow widget.

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

@@ -193,6 +193,7 @@ export interface INotebookEditor extends IEditor {
 
 	getId(): string;
 	getDomNode(): HTMLElement;
+	getOverflowContainerDomNode(): HTMLElement;
 	getInnerWebview(): Webview | undefined;
 
 	/**

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

@@ -76,6 +76,7 @@ export class NotebookEditorWidget extends Disposable implements INotebookEditor
 	private static readonly EDITOR_MEMENTOS = new Map<string, EditorMemento<unknown>>();
 	private _overlayContainer!: HTMLElement;
 	private _body!: HTMLElement;
+	private _overflowContainer!: HTMLElement;
 	private _webview: BackLayerWebView | null = null;
 	private _webviewResolved: boolean = false;
 	private _webviewResolvePromise: Promise<BackLayerWebView | null> | null = null;
@@ -356,6 +357,11 @@ export class NotebookEditorWidget extends Disposable implements INotebookEditor
 		DOM.addClass(this._body, 'cell-list-container');
 		this._createCellList();
 		DOM.append(parent, this._body);
+
+		this._overflowContainer = document.createElement('div');
+		DOM.addClass(this._overflowContainer, 'notebook-overflow-widget-container');
+		DOM.addClass(this._overflowContainer, 'monaco-editor');
+		DOM.append(parent, this._overflowContainer);
 	}
 
 	private _createCellList(): void {
@@ -484,6 +490,10 @@ export class NotebookEditorWidget extends Disposable implements INotebookEditor
 		return this._overlayContainer;
 	}
 
+	getOverflowContainerDomNode() {
+		return this._overflowContainer;
+	}
+
 	onWillHide() {
 		this._isVisible = false;
 		this._editorFocus?.set(false);

src/vs/workbench/contrib/notebook/browser/view/renderers/cellRenderer.ts

@@ -992,7 +992,8 @@ export class CodeCellRenderer extends AbstractCellRenderer implements IListRende
 			dimension: {
 				width: 0,
 				height: 0
-			}
+			},
+			overflowWidgetsDomNode: this.notebookEditor.getOverflowContainerDomNode()
 		}, {});
 
 		disposables.add(this.editorOptions.onDidChange(newValue => editor.updateOptions(newValue)));

src/vs/workbench/contrib/notebook/browser/view/renderers/markdownCell.ts

@@ -189,7 +189,8 @@ export class StatefulMarkdownCell extends Disposable {
 				dimension: {
 					width: width,
 					height: editorHeight
-				}
+				},
+				overflowWidgetsDomNode: this.notebookEditor.getOverflowContainerDomNode()
 			}, {});
 			this.templateData.currentEditor = this.editor;
 

src/vs/workbench/contrib/notebook/test/testNotebookEditor.ts

@@ -103,6 +103,10 @@ export class TestNotebookEditor implements INotebookEditor {
 		throw new Error('Method not implemented.');
 	}
 
+	getOverflowContainerDomNode(): HTMLElement {
+		throw new Error('Method not implemented.');
+	}
+
 	private _onDidChangeModel = new Emitter<NotebookTextModel | undefined>();
 	onDidChangeModel: Event<NotebookTextModel | undefined> = this._onDidChangeModel.event;
 	getContribution<T extends INotebookEditorContribution>(id: string): T {