src/vs/workbench/browser/parts/views/treeView.ts/TreeView/focus
class TreeView:	focus(reveal: boolean = true): void {
		if (this.tree && this.root.children && this.root.children.length > 0) {
			// Make sure the current selected element is revealed
			const selectedElement = this.tree.getSelection()[0];
			if (selectedElement && reveal) {
				this.tree.reveal(selectedElement, 0.5);
			}

			// Pass Focus to Viewer
			this.tree.domFocus();
		} else if (this.tree) {
			this.tree.domFocus();
		} else {
			this.domNode.focus();
		}
	}