scenario:

The tree_selection mode of my tree is GTK_SELECTION_NONE all my cell-renderers
are not editable. This way I get a gray rectangle denoting the current row.
I still can use cursor left, right to move between columns, but there is no gray
rectangle around the columns. Is there anything I can do to highlight the column
that has the foucs too. What I am looking for is something like

Pos  Col1 Col2 Col3
     +---+
 0   | a |  x    y
+----+---+---------+
|1   | b |  c    f |
+----+---+---------+
 2   | d |  z    u
     |   |
 3   | e |  v    w
     +---+

Basically I want the user to browse around, where one cell is always selected
(GTK_SELECTION_BROWSE unfortunately selects whole rows) and via
key-release-event I change the data in the cell.
The active cell should not be moveable to the "Pos." column (see previous mail
about "not focuasable treeview columns).