"The main focus for GIMP 2.6 was the implementation of GEGL.
While most users won't notice the changes under the surface, some
things can be seen clearly:
"The duplicate file menu entries (one in the toolbox and one in
the image window) are gone. From now on, only one file menu will be
displayed in the image window, so there's always at least one
window opened which contains the entry, even if there is no image
open (then a grey container is displayed) changes to the user
interface..."