Select All/Deselect All in a Table view

Hi All,

In an Overview Page, I have header view and an Assignment Block. Based on a Header view attribute value, I am MARKing the Rows in Assignment block through Comp Controller method.  I see all rows in Assignment Block are getting MARKed. When I checked the Select All / Deselect All button towards the left top most corner of the Table view, its showing 'Select All' even though all rows are already selected. Please find the screen shot below.

How do we manually toggle between "Select All" and "Deselect All" in this case or Which Context node parameter needs to be Set in order to switch to Deselect All.

Thanks & Regards

Anji