React Tabbar, update page when not passing explicit prop in.

[cjweigle]

This fixed issue #2335 for me. I've only tested by wrapping the component, haven't had a chance to rebuild and test this patch to the library yet.

Wrapper for component:
https://gist.github.com/chronweigle/c7bf3b5a7ad21dbbb5110236439ad4f6

[asialgearoid]

@chronweigle I'm not sure why this PR was not responded to originally, sorry for the delay.

I've tested it out, and it doesn't appear to actually fix the issue described in #2335. I can imagine this might fix issues where you were dynamically setting the active tab. However it does not seem to fix the issue where changing the actual tabs does not update the pages which the tabs relate to.

[cjweigle]

I mentioned I hadn't tested it. Looking at this now I see it shouldn't work. I missed hooking into the onPostChange callback as I did in the wrapper in the gist.

I've opened a new PR and provided an explanation. I spent more time providing an explanation of the problem than the solution since I don't know if this is the ideal solution. A proper understanding of the problem should lead you to a solution.

Thank you

#2508