notifyDataSetChanged() do not call onBindLeftTopHeaderViewHolder but does to every other header

[vyguera]

I am implementing a sort action when clicking on any column header. What also concerns top left corner header.

Table is sorted by top left corner header by default. If user clicks on any other column header, table becomes sorted by that column. I maintain the visibility of a drawable on headers to show if it is sorting ascending or descending

When playing between column headers everything works correctly. This is, if I click on any column header onBindHeaderColumnViewHolder is called and this drawable is removed from previous column and turns visible on new column header. But drawable is never removed from top left corner header as onBindLeftTopHeaderViewHolder is never called too.

[vyguera]

This is solved on pull request #41.