we need to allow for columns to have a primary and secondary sort. the UI should allow for a way to click on second column which you want to sort by after the primary sort. one way to do this is via holding down the shift key like this jquery plugin does it. initial secondary sort direction should be configuring and a second secondary sort click should allow the column to be sorted in the opposite direction and then turned off on the 3rd click.

As well, we should allow for programmatic access to this so when an under users clicks on column A, the js can be configured to automatically have column B be the secondary sort ASC or DESC.