Since May 17th, GtkTreeView cell edits show up unconditionally at the beginning of the row, instead of at the cell location.

This was broken by the following commit:

commit 6f9dc0ffd73ba2be7f457b1311f024d1bed0e1db
Author: Benjamin Otte <otte@redhat.com>
Date:   Fri May 17 14:28:18 2013 +0200

    treeview: Store editable position differently
    
To see the broken behaviour, build master and run:
  ./tests/testtreeedit

Luckily the patch in question is atomic enough to simply revert, to see the
proper functionality, simply try reverting the above patch and run
testtreeedit again.

Note that since the above patch, the cell editable widget takes up the whole
row instead of the cell's area.