Using the Photoshop Layers
When you configure a PSD file for use as a layered menu, you select the layer or layers
that provide the menu’s background. The background can include all of the buttons’
normal state, but it doesn’t have to. If the background includes the normal state, the
selected and activated states must be configured to take into account that the normal
state is always present. If you want the button to change significantly when switching to
the selected and activated states, you may need to have the normal state on its own layer
so that it can be hidden when the other states appear.