Basics - GIMP 2.6 for Photographers: Image Editing with Open Source Software - page 35

The Toolbox and the dock are placed on the background together with the
frame, taking up only one tab on the taskbar. You can find this setting by
choosing Edit > Preferences > Window Management . Choose Window Manager
Hints: Utility Window and then save by clicking Save Window Positions Now .
After restarting GIMP and maximizing your image window, you can place
your Toolbox and the dock on the image window. This technique works on
Windows, Linux, and Mac OS X since GIMP 2.6.2. All three windows are visible
on a single button of your taskbar or your Windows Manager. However, GIMP
hasn't been developed completely, so the Toolbox and the dock are not
minimized when the image window is minimized. At least, this is true for the
Windows version of GIMP.
Figure 1.14
The program windows after the first start on Windows Vista. In the current version, GIMP 2.6.8, three separate windows open: the
image window, the Toolbox with a selection of tools and the docked Tool settings, and the dock with the Layers, Channels, Paths,
and Undo windows in the upper row and the Brushes, Patterns, and Gradients windows below.