Duplicate File Detective has a huge variety of functional and user interface customization options.
Toolbars, Menus and Status Bar
Right-clicking in the area of the menu bar or toolbar will reveal a menu that allows you to further customize nearly every aspect of these interfaces.
The visibility of application toolbars (as well as the status bar at the bottom of the screen) can be controlled via the View menu.
Docking Panels
Any of the panels that appear by default on the right and left of the main application window can be docked, undocked, hidden, or closed entirely. Simply click the caption bar of one of the panels (the Filter Criteria panel, for example) and drag the mouse to move the panel. A series of guides will appear that help you to visualize and access the available docking positions. You can even dock a panel inside of another docking panel, in which case it appears as an additional tab within the panel frame.
The visibility of Docking Panels can also be manipulated via the View | Docking Panels menu selection.
Report Options
Right-clicking the duplicate file report column header will allow you to add and remove report columns, alter column alignment, and more. Report columns can also be managed via the View | Report Field Chooser menu item - when the field chooser window appears, you can drag report columns from it and drop them onto the report detail area (the reverse can also be used to remove them).
Duplicate file report columns can also be re-ordered simply by dragging and dropping.
Additional report options can be found by clicking the main View menu, which contains options for controlling how the report displays file sizes, the report grid style, how grouping is performed, shading of report group headers, and more.
Global Preferences
Some report customization options (such as attribute colors) are located within the global preferences window, accessible via the main Tools menu.