Used by GUIUtility.GetControlID to inform the UnityGUI system if a given control can get keyboard focus.
| Native | This control can get keyboard focus on Windows, but not on Mac. Used for buttons, checkboxes and other "pressable" things. |
| Keyboard | This is a proper keyboard control. It can have input focus on all platforms. Used for TextField and TextArea controls. |
| Passive | This control can never recieve keyboard focus. |