fixes microsoft#166552 (microsoft#166594)

Author: joaomoreno

src/vs/base/browser/ui/tree/abstractTree.ts

@@ -1266,11 +1266,10 @@ class TreeNodeListMouseController<T, TFilterData, TRef> extends MouseController<
 		}
 
 		if (node.collapsible) {
-			const model = this.tree.model; // internal
-			const location = model.getNodeLocation(node);
+			const location = this.tree.getNodeLocation(node);
 			const recursive = e.browserEvent.altKey;
 			this.tree.setFocus([location]);
-			model.setCollapsed(location, undefined, recursive);
+			this.tree.toggleCollapsed(location, recursive);
 
 			if (expandOnlyOnTwistieClick && onTwistie) {
 				return;
@@ -1389,7 +1388,7 @@ export abstract class AbstractTree<T, TFilterData, TRef> implements IDisposable
 
 	protected view: TreeNodeList<T, TFilterData, TRef>;
 	private renderers: TreeRenderer<T, TFilterData, TRef, any>[];
-	model: ITreeModel<T, TFilterData, TRef>; // used in MouseController
+	protected model: ITreeModel<T, TFilterData, TRef>;
 	private focus: Trait<T>;
 	private selection: Trait<T>;
 	private anchor: Trait<T>;
@@ -1666,6 +1665,10 @@ export abstract class AbstractTree<T, TFilterData, TRef> implements IDisposable
 		return this.model.getNode(location);
 	}
 
+	getNodeLocation(node: ITreeNode<T, TFilterData>): TRef {
+		return this.model.getNodeLocation(node);
+	}
+
 	collapse(location: TRef, recursive: boolean = false): boolean {
 		return this.model.setCollapsed(location, true, recursive);
 	}

src/vs/base/browser/ui/tree/dataTree.ts

@@ -16,7 +16,7 @@ export interface IDataTreeOptions<T, TFilterData = void> extends IAbstractTreeOp
 
 export class DataTree<TInput, T, TFilterData = void> extends AbstractTree<T | null, TFilterData, T | null> {
 
-	declare model: ObjectTreeModel<T, TFilterData>;
+	protected declare model: ObjectTreeModel<T, TFilterData>;
 	private input: TInput | undefined;
 
 	private identityProvider: IIdentityProvider<T> | undefined;

src/vs/base/browser/ui/tree/indexTree.ts

@@ -14,7 +14,7 @@ export interface IIndexTreeOptions<T, TFilterData = void> extends IAbstractTreeO
 
 export class IndexTree<T, TFilterData = void> extends AbstractTree<T, TFilterData, number[]> {
 
-	declare model: IndexTreeModel<T, TFilterData>;
+	protected declare model: IndexTreeModel<T, TFilterData>;
 
 	constructor(
 		user: string,

src/vs/base/browser/ui/tree/objectTree.ts

@@ -45,7 +45,7 @@ export interface IObjectTreeViewState {
 
 export class ObjectTree<T extends NonNullable<any>, TFilterData = void> extends AbstractTree<T | null, TFilterData, T | null> {
 
-	declare model: IObjectTreeModel<T, TFilterData>;
+	protected declare model: IObjectTreeModel<T, TFilterData>;
 
 	override get onDidChangeCollapseState(): Event<ICollapseStateChangeEvent<T | null, TFilterData>> { return this.model.onDidChangeCollapseState; }
 
@@ -197,7 +197,7 @@ export interface ICompressibleObjectTreeOptionsUpdate extends IAbstractTreeOptio
 
 export class CompressibleObjectTree<T extends NonNullable<any>, TFilterData = void> extends ObjectTree<T, TFilterData> implements ICompressedTreeNodeProvider<T, TFilterData> {
 
-	declare model: CompressibleObjectTreeModel<T, TFilterData>;
+	protected declare model: CompressibleObjectTreeModel<T, TFilterData>;
 
 	constructor(
 		user: string,