It’s been 5 years since GIMP’s last overhaul so this one’s been overdue. It now has a single window editing mode, although the multi window mode is the default. It can be changed in the “Windows” menu, and the preference will be remembered.
Ars Technica has a ‘hands on’ review which might be more informative to read, as I’d only be quoting and I’ve never used GIMP.
GIMP also gained a number of other design and usability improvements. The title bar on the floating palette w...