Bring all windows to the front when switching
To cause all windows of an application to be brought to the front when you switch to it, check this box.
Hide other applications when switching
To hide all other applications when you switch to a particular application, check this box.
Only hide when switching using DragThing
To make DragThing only hide other applications when you switch to them using a DragThing dock or hot key, check this box.
This affects the behaviour of the "Hide other applications when switching" option which normally hides applications regardless of how you switch.
Edit List of Never Hidden Applications
To show a window where you can choose which applications are not to be hidden by DragThing, click this button.
You can drag applications into the list to add them, or use the Add and Remove buttons.