[pygtk] cellrendertext to stay in edit mode.

[Mike Bernson]

What I am trying to do is build a treeview that has a number of columns with cellrendertext
in them.

I want to change the way editing works so that when a user hits up arrow or down arrow key
the current cell finish editing and the cell above or below starts editing.

What I current see is that up arrow or down arrow key finish edit for the current cell but
does not move the cursor. I have to hit arrow key again and then the start edit on this cell.

I would also like the tab key to handle move on the same line while in edit. (left and right
arrows are in use by the entry widget).

If the treeview/columns/cellrenderers can not handle this is there a better way handled this.