[TIMOB-16912][TIMOB-8222] TabGroup fixes

Fixes 
[TIMOB-16912](https://jira.appcelerator.org/browse/TIMOB-16912)
[TIMOB-8222](https://jira.appcelerator.org/browse/TIMOB-8222)

Regress against
[TIMOB-16184](https://jira.appcelerator.org/browse/TIMOB-16184)