TreeGrid mode and Column sorting

[desarrollo03TR]

I'm implementing a custom grouping with a custom comprarer for a grid in TreeGrid mode.

What I want is to apply an specific sort for each cell in specific column (each group should be sorted using an specific comparer). I'm initializing the ItemsComparer prop (from OutlookGridDefaultGroup) with a class that implements IComparer but it looks like only the header row from the group is sorted.