Source -
deviantARTThe news already has its time, but continues to impact on those who have not seen. Most of us are already aware about GIMP 2.7.3(unstable) and its single window interface. This is one of those significant improvements in the field of open-source graphic softwares.
The single window option exist and you can test it in the GIMP 2.7.1. You can download it at any time and give a test, but be warned that it will remove your current version of GIMP and replace it by this 2.7.1, so if you want to test, be sure to back up your plugins and whatever settings.
In my experience the Gimp 2.7.3 release is a bit buggy currently, as after activating the option, once you closed GIMP, and relaunched it , GIMP was forgetting that it was in single window mode and went back to floating panels, leading you to reset it correctly each time. And for now, the docks are stuck with the single window, meaning you can't move them in a position that would satisfy you better into this single window.
Tasks left on GIMP 2.8Write release notes
Announce string freeze
Decide on a splash image
Bug 631934 - Interaction between Old text parameters and new region specific text attributes
Bug 51112 - Support layer masks on layer groups
Single-window mode related bugfixing buffer
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If you consider testing Gimp 2.7.3(unstable)
GIMP 2.7.3 can be downloaded as source at the official GIMP website.
To install on Ubuntu add ’ppa:matthaeus123/mrw-gimp-svn’ to your Software Sources. Following this either update and upgrade your existing GIMP installation, or update and install GIMP via the Ubuntu Software Center.