src/vs/base/browser/ui/actionbar/actionbar.ts/ActionBar/focusNext
class ActionBar:	protected focusNext(forceLoop?: boolean): boolean {
		if (typeof this.focusedItem === 'undefined') {
			this.focusedItem = this.viewItems.length - 1;
		} else if (this.viewItems.length <= 1) {
			return false;
		}

		const startIndex = this.focusedItem;
		let item: IActionViewItem;
		do {

			if (!forceLoop && this.options.preventLoopNavigation && this.focusedItem + 1 >= this.viewItems.length) {
				this.focusedItem = startIndex;
				return false;
			}

			this.focusedItem = (this.focusedItem + 1) % this.viewItems.length;
			item = this.viewItems[this.focusedItem];
		} while (this.focusedItem !== startIndex && ((this.options.focusOnlyEnabledItems && !item.isEnabled()) || item.action.id === Separator.ID));

		this.updateFocus();
		return true;
	}