From RoboBlitz Editor Wiki
The Browser Window is your primary view into the resources available to a map maker or modder. It contains information on all the currently loaded resources, levels, classes and packages. It also allows you to apply these resources to a map or to other resources.
Using the Browser Window
To open the browser window, click View->Browser Windows and then choose one of the options in the first section. Or open the Generic Browser by clicking this icon in the top toolbar:
Each of these options corresponds to a tab in the Browser Window. Once the window is open you can switch between the different browser windows by clicking the tabs. The browser window looks like this:
The Generic Browser contains art resources and other assets, as well as Archetypes.
Actor Classes Browser
The Actor Classes browser contains a list of all the classes available to the editor. Creating a class from this window intializes it to it's default values. Be warned, sometimes these defaults are unusuable!
The Level Browser allows you to select which levels are visible. If you open one of the RoboBlitz Maps, you'll notice that the aspects of the map which are shared across all three levels (for instance, Radar 1, Radar 2, and Radar 3) are in the Persistant Level. Anything which is used by only one of the levels (like a Noed SpawnPad, or dynamic actors) is only in the level it pertains to. You can hide or show each of these levels with the "Visible?" option. You can also access the Kismet for each level or in the Persistant Level from the Level Browser.
Primitive Stats Browser
The Primitive Stats Browser shows statistics on aspects of the level which will affect graphics performance.