I've been following the demo's provided on the Kendo site and attempting to add several features into a grid: The selectable feature to allow click-drag selection of multiple rows, and a "Select All" checkbox in the header that will select all checkboxes for all available rows.
Unfortunately, I have not been able to get them both to work at the same time. Please see the Dojo I've modified: Here
Notice that the "select all" checkbox works correctly on page load - but when a feature of the grid is interacted with (such as the sort feature), the checkbox will stop working. Here's the interesting thing, if another feature is clicked (another sort - even if not the same row), the checkbox will function correctly again.
It "feels" as though something is being enabled/disabled that allows the checkbox to be selected.