src/vs/workbench/browser/parts/views/viewPaneContainer.ts/ViewPaneContainer/focus
class ViewPaneContainer:	focus(): void {
		if (this.lastFocusedPane) {
			this.lastFocusedPane.focus();
		} else if (this.paneItems.length > 0) {
			for (const { pane: pane } of this.paneItems) {
				if (pane.isExpanded()) {
					pane.focus();
					return;
				}
			}
		}
	}