JimYTC/GridViewHeader — pull request #1 by JimYTC (2014-08-26 03:13:08+00:00)
Title: Return items enabled related function

Implement these two methods.

For ```areAllitemsEnabled()```, because there are placeholders that would not be obtained from original adapter, this method should always returns ```false```.

In order to tell system invoking ```onItemClick``` or not, we have to invoke ```isEnabled(int position)``` of the original adapter with ```position -= getnumColumnsCompat()``` which is the real item index.