How to expand/collapse a certain level of groups?

[hightow]

I can't find example code where I can expand/collapse a certain level of groups by code.

ExpandAllGroups() expands all groups, while ExpandGroup() expand one certain group-item.

Say I have a grid that are grouped by colA and colB.
When pressing one button (or whatever) I want all colA-items to be expanded.
When pressing another button I want all colA- and all colB-items to be expanded.

How do I do that?

Thanks for any reply