Flipping a TreeView

[Duncan Sands <baldrick free fr>]

Dear gurus, I have a treeview which looks like this:

A	1.0		B
C	2.0		D
...
Y	25.0		Z


This reflects the model (which needs to be like this because
all elements of a column must have the same type).

I would like it to be displayed like this:

A	C	...	Y
1.0	2.0	...	25.0
B	D	...	Z

i.e. flipped (transposed).  Is there some flag that can be set to do this?

Thanks a lot,

Duncan.