tree: expose things for debug

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

@@ -399,6 +399,12 @@ export abstract class AbstractTree<T, TFilterData, TRef> implements IDisposable
 		return this.view.getRelativeTop(index);
 	}
 
+	// List
+
+	get visibleNodeCount(): number {
+		return this.view.length;
+	}
+
 	private reactOnMouseClick(e: IListMouseEvent<ITreeNode<T, TFilterData>>): void {
 		const node = e.element;
 

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

@@ -124,6 +124,7 @@ export class DataTree<T extends NonNullable<any>, TFilterData = void> implements
 
 	get onDidChangeFocus(): Event<ITreeEvent<T>> { return mapEvent(this.tree.onDidChangeFocus, asTreeEvent); }
 	get onDidChangeSelection(): Event<ITreeEvent<T>> { return mapEvent(this.tree.onDidChangeSelection, asTreeEvent); }
+	get onDidChangeCollapseState(): Event<T> { return mapEvent(this.tree.onDidChangeCollapseState, e => e.element.element); }
 
 	get onMouseClick(): Event<ITreeMouseEvent<T>> { return mapEvent(this.tree.onMouseClick, asTreeMouseEvent); }
 	get onMouseDblClick(): Event<ITreeMouseEvent<T>> { return mapEvent(this.tree.onMouseDblClick, asTreeMouseEvent); }
@@ -156,6 +157,10 @@ export class DataTree<T extends NonNullable<any>, TFilterData = void> implements
 		this.tree.onDidChangeCollapseState(this._onDidChangeCollapseState, this, this.disposables);
 	}
 
+	domFocus(): void {
+		this.tree.domFocus();
+	}
+
 	layout(height?: number): void {
 		this.tree.layout(height);
 	}
@@ -253,6 +258,10 @@ export class DataTree<T extends NonNullable<any>, TFilterData = void> implements
 
 	// Tree
 
+	get visibleNodeCount(): number {
+		return this.tree.visibleNodeCount;
+	}
+
 	collapse(element: T): boolean {
 		return this.tree.collapse(this.getNode(element));
 	}