GroIMP's user interface consists of an arrangement of panels, e.g., a 3D view or a text editor. This arrangement can be changed by the user by Drag&Drop: For panels with title bars or panels in a tab group, a Drag&Drop operation is performed by dragging title bars with the mouse. A contour indicates where the panel will be dropped if you release the mouse button. For panels without title bars (e.g., toolbars, statusbars), just drag the panels themselves.

Every panel has a panel menu which provides at least the operations Undock and Close. A panel menu is opened by clicking on the title bar of the panel or, if there is no title bar, on the panel itself (usually with the right mouse button). The Undock operation undocks the panel out of its current location and brings it up in a new floating window, the Close operation closes a panel.

Normally, not all possible panels are actually present in the user interface. However, all panels are accessible through the Panels menu of GroIMP's main window. If a panel you need is missing, just select it in the main Panels menu. This brings up the panel in a new floating window.

The arrangement of all panels is called a panel layout. The menu Panels/Set Layout provides a set of predefined layouts which are useful for distinct tasks; the menu item Panels/Add Layout adds the current layout to the list of user-defined layouts of the current project. User-defined layouts are also accessible in the menu Panels/Set Layout.