Tool box and Tools option docks are usually placed to the left in the user interface and layers, histogram and other windows are placed in the right of the workspace but their position can easily be changed according to your choice.
Although the separated windows may disturb those users who are used to Photoshop layouts, your comfort level would grow as you discover how pain-free the program is. These docks are fully customizable and can be hidden or expanded by dragging their edges. From the window menu you can customize the number of docks which would remain open or closed. The layout of GIMP 2.6.11 is very much similar to that of Adobe Photoshop, and actually consists of many docks (Tool box, Tool option, Layer, Histogram windows are called docks in GIMP) that you can move around as per your convenience.
