src/vs/base/browser/ui/actionbar/actionbar.ts/ActionBar/setFocusable
class ActionBar:	setFocusable(focusable: boolean): void {
		this.focusable = focusable;
		if (this.focusable) {
			const firstEnabled = this.viewItems.find(vi => vi instanceof BaseActionViewItem && vi.isEnabled());
			if (firstEnabled instanceof BaseActionViewItem) {
				firstEnabled.setFocusable(true);
			}
		} else {
			this.viewItems.forEach(vi => {
				if (vi instanceof BaseActionViewItem) {
					vi.setFocusable(false);
				}
			});
		}
	}