Navigation Palette. The palette allows you to change visibility of layers and classes, change view options for design layers, classes, sheet layers viewports and saved views, create, edit and design layers, classes, sheet layers viewports and saved views.
Using the right mouse click on the Navigation Palette gives you access to a menu. This can be used to create, edit, duplicate, delete and so on. I keep this palette open all the time now. I have been using so often I forgot where the class button was the other day, it had been so long since I used it.