Click the Delete Layer button to delete the currently selected layer. A dialog box will show up and ask for confirmation.
Once a layer is deleted, it cannot be restored without reloading a previous version of the level, or re-importing the layer if it was external.
Does the same thing as the layer hide/show icon. See below for more information.
Does the same thing as the layer freeze/unfreeze icon. See below for more information.
Export Layer Pak
This layer will be loaded by default.
When this checkbox is enabled, the layer will be stored as a separate .lyr file on disk, enabling better use of version control systems.
Export to Game
When this checkbox is enabled, the layer will be exported to the game when you use File -> Export to engine.
Brushes Have Physics
Brushes within a layer with this disabled will not have physics. This is good for distance background objects to save on performance.
By default any object is placed in the layer "Main", unless you have selected another from the layers menu.
If a different layer is selected from the Layers tab, any objects added to the level will automatically be assigned to that layer.