Unity Script Reference:

static function Foldout(foldout: bool, content: string, style: GUIStyle = EditorStyles.foldout): bool;

static bool Foldout(bool foldout, string content, GUIStyle style = EditorStyles.foldout);

static def Foldout(foldout as bool, content as string, style as GUIStyle = EditorStyles.foldout) as bool

static function Foldout(foldout: bool, content: GUIContent, style: GUIStyle = EditorStyles.foldout): bool;

static bool Foldout(bool foldout, GUIContent content, GUIStyle style = EditorStyles.foldout);

static def Foldout(foldout as bool, content as GUIContent, style as GUIStyle = EditorStyles.foldout) as bool

Parameters

foldout	The shown foldout state.
content	The label to show.
style	Optional GUIStyle.

Returns
bool The foldout state selected by the user. If true, you should render sub-objects.

Description

Make a label with a foldout arrow to the left of it.

This is useful for creating tree or folder like structures where child objects are only shown if the parent is folded out.

Create a foldable menu that hides/shows the selected transform.

	// Create a foldable menu that hides/shows the selected transform
	// position.
	// if no Transform is selected, the Foldout item will be folded until
	// a transform is selected.
	
	class FoldoutUsage extends EditorWindow {
	
		var showPosition : boolean = true;
		var status : String = "Select a GameObject";
		@MenuItem("Examples/Foldout Usage")
		static function Init() {
			var window = GetWindow(FoldoutUsage);
			window.Show();
		}
		
		function OnGUI() {
			showPosition = EditorGUILayout.Foldout(showPosition, status);
			if(showPosition)
				if(Selection.activeTransform) {
					Selection.activeTransform.position = 
						EditorGUILayout.Vector3Field("Position", Selection.activeTransform.position);
						status = Selection.activeTransform.name;
				}
			
			if(!Selection.activeTransform) {
				status = "Select a GameObject";
				showPosition = false;	
			}
		}
		function OnInspectorUpdate() {
			this.Repaint();
		}
	}