I need to support multi-column sorting but I only want it to work if the user utilizes a modifier key (like shift-click, ctrl-click, or alt-click). When the user does not use a modifier key, I need each column click to sort just the one column and undo any previous column sorting.
In testing, my users found the default behavior very confusing. They expected each column click to immediate sort just that one column unless they specifically used an option to do a multi-column sort (users suggested shift-click and ctrl-click).
Any thoughts on how to accomplish this without modifying the api?