dojox data grid - hook to find if the header checkbox is selected or not

In a multiple selection grid, is there a hook to check if the check box in the header is checked or unchecked. Currently to see if all rows are selected, i am using grid.selection.getSelected().length which returns the no of selected rows and with more that 2500 rows in grid, IE throws script error. To optimize we just nee开发者_如何学God a hook to check if the header checkbox is checked or unchecked.

grid.selection.getSelectedCount() works without loading all the items.

getSelected() with indirect selection attempts to load all the items.