src/vs/base/browser/ui/tree/abstractTree.ts/AbstractTree/onSpace
class AbstractTree:	private onSpace(e: StandardKeyboardEvent): void {
		e.preventDefault();
		e.stopPropagation();

		const nodes = this.view.getFocusedElements();

		if (nodes.length === 0) {
			return;
		}

		const node = nodes[0];
		const location = this.model.getNodeLocation(node);
		const recursive = e.browserEvent.altKey;

		this.model.setCollapsed(location, undefined, recursive);
	}