mleibman/SlickGrid — pull request #833 by luisvt (2013-12-18 23:36:28+00:00)
Title: Update slick.checkboxselectcolumn.js

When working with Row Grouping the "header checkbox" is never selected, for that reason we need to change line 54.

It is never selected because you are comparing selectedRows.lenght with _grid.getDataLength() which returns the values of the rendered rows and not the value of the dataView.Items.

The exmple code to test that is as fallow:

```

SlickGrid example: Grouping

```