How to add a column of NSButtonCells to an NSOutlineView in InterfaceBuilder?

FROM : James Stein
DATE : Sun Mar 23 22:52:50 2008

I'm tearing out my hear trying to figure this out,or find the documentation
(if any) on how to do it.
But it must be really simple.

Example:
In Interface builder, I have an NSOutlineView with
two columns, a column of NSTextFieldCell and
a column of NSButtonCell.

By changing the number of columns from 2 to 3
in the inspector window for the outline view,
another column is created, but by default
it is a column of NSTextFieldCell.

The inspector for the NSTextFieldCell won't let
me change its type to NSButtonCell.

Neither of the inspectors for the TableColumn and the
OutlineView seem to offer any solutions either.

I've tried copying the column of Button cells
and pasting it onto the new column, but IB
insists on pasting into the top level of the nib file,
not onto the new column.  Similarly if I try to drag
an NSButtonCell onto the NSTextFieldCell
or TableColumn, IB places it at the top level of the nib file.

What am I missing, overlooking, not finding?