fix tree layout, add proposed API

src/vscode-dts/vscode.proposed.notebookVariableProvider.d.ts

@@ -0,0 +1,43 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the MIT License. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+declare module 'vscode' {
+
+	export interface NotebookController {
+		/** Set this to attach a variable provider to this controller. */
+		variableProvider?: NotebookVariableProvider;
+	}
+
+	export enum VariablesRequestKind {
+		Named,
+		Indexed
+	}
+
+	interface VariablesResult {
+		variable: Variable;
+		namedVariableCount: number;
+		indexedVariableCount: number;
+	}
+
+	interface NotebookVariableProvider {
+		onDidChangeVariables: Event<void>;
+
+		/** When variablesReference is undefined, this is requesting global Variables. When a variable is passed, it's requesting child props of that Variable. */
+		provideChildren(notebook: NotebookDocument, variable: Variable | undefined, kind: VariablesRequestKind, start: number, token: CancellationToken): AsyncIterable<VariablesResult>;
+	}
+
+	interface Variable {
+		/** The variable's name. */
+		name: string;
+
+		/** The variable's value.
+			This can be a multi-line text, e.g. for a function the body of a function.
+			For structured variables (which do not have a simple value), it is recommended to provide a one-line representation of the structured object.
+			This helps to identify the structured object in the collapsed state when its children are not yet visible.
+			An empty string can be used if no value should be shown in the UI.
+		*/
+		value: string;
+	}
+
+}