The contents of a GUI element.
This works closely in relation with GUIStyle. GUIContent defines what to render and GUIStyle defines how to render it.
Additional resources: GUIStyle.
| none | Shorthand for empty content. |
| image | The icon image contained. |
| text | The text contained. |
| tooltip | The tooltip of this element. |
| GUIContent | Constructor for GUIContent in all shapes and sizes. |