diff --git a/src/Pyramid-Bloc/PyramidBlocPlugin.class.st b/src/Pyramid-Bloc/PyramidBlocPlugin.class.st
index 0e8b6e10..51abeb67 100644
--- a/src/Pyramid-Bloc/PyramidBlocPlugin.class.st
+++ b/src/Pyramid-Bloc/PyramidBlocPlugin.class.st
@@ -84,6 +84,47 @@ PyramidBlocPlugin class >> visibility [
 	^ property
 ]
 
+{ #category : #accessing }
+PyramidBlocPlugin class >> visibility2 [
+
+	| property |
+	property := PyramidProperty new
+		            name: 'Visibility2';
+		            command: PyramidVisibilityCommand new;
+		            inputPresenterClass: PyramidMagicButtonsInputPresenter;
+		            yourself.
+	property inputPresenterModel
+		addButtonModel: (PyramidMagicButtonModel new
+				 icon: (Smalltalk ui icons iconNamed: #windowMaximize);
+				 helpSelected: 'The object is visible.';
+				 helpNotSelected: 'Set the value to visible.';
+				 label: 'Visible';
+				 inputValue: [ BlVisibility visible ];
+				 inputValidation: [ :value | value isVisible ];
+				 yourself);
+		addButtonModel: (PyramidMagicButtonModel new
+				 icon: (Smalltalk ui icons iconNamed: #windowMaximize);
+				 helpSelected:
+					 'The object is hidden. (Still computed for the layout)';
+				 helpNotSelected:
+					 'Set the value to hidden. (Still computed for the layout)';
+				 label: 'Hidden';
+				 inputValue: [ BlVisibility hidden ];
+				 inputValidation: [ :value |
+					 value isHidden and: [ value isGone not ] ];
+				 yourself);
+		addButtonModel: (PyramidMagicButtonModel new
+				 icon: (Smalltalk ui icons iconNamed: #windowMaximize);
+				 helpSelected: 'The object is gone. (Not computed for the layout)';
+				 helpNotSelected:
+					 'Set the value to gone. (Not computed for the layout)';
+				 label: 'Gone';
+				 inputValue: [ BlVisibility gone ];
+				 inputValidation: [ :value | value isGone ];
+				 yourself).
+	^ property
+]
+
 { #category : #accessing }
 PyramidBlocPlugin class >> zIndex [
 
@@ -192,13 +233,14 @@ PyramidBlocPlugin >> groupMenuBlockSingle [
 PyramidBlocPlugin >> initialize [
 
 	super initialize.
-	
+
 	groupCommand := PyramidGroupCommand new.
-	
+
 	propertiesManager := PyramidPropertiesManagerForSelection new.
 
 	propertiesManager addProperty: self class elementId.
 	propertiesManager addProperty: self class visibility.
+	propertiesManager addProperty: self class visibility2.
 	propertiesManager addProperty: self class zIndex.
 	propertiesManager addProperty: self class clipChildren.
 	propertiesManager addProperty: self class geometry.
diff --git a/src/Pyramid-Bloc/PyramidElementsManipulationHelper.class.st b/src/Pyramid-Bloc/PyramidElementsManipulationHelper.class.st
index 30c82f83..b1afef44 100644
--- a/src/Pyramid-Bloc/PyramidElementsManipulationHelper.class.st
+++ b/src/Pyramid-Bloc/PyramidElementsManipulationHelper.class.st
@@ -36,6 +36,17 @@ PyramidElementsManipulationHelper class >> accumulateParentsOf: aCollectionOfBlE
 	self accumulateParentsOf: nextCollection in: result
 ]
 
+{ #category : #'as yet unclassified' }
+PyramidElementsManipulationHelper class >> countElementsIn: aCollection [
+
+	| result |
+	aCollection ifEmpty: [ ^ 0 ].
+	result := aCollection size.
+	aCollection do: [ :each |
+		result := result + (self recursiveCountElementsIn: each) ].
+	^ result
+]
+
 { #category : #'as yet unclassified' }
 PyramidElementsManipulationHelper class >> flattenChildrenOfCollection: aCollection [
 	"Consider:
@@ -79,3 +90,13 @@ PyramidElementsManipulationHelper class >> onlyParents: aCollectionOfBlElement [
 	self accumulateParentsOf: aCollectionOfBlElement in: result.
 	^ result asArray
 ]
+
+{ #category : #'as yet unclassified' }
+PyramidElementsManipulationHelper class >> recursiveCountElementsIn: aBlElement [
+
+	| result |
+	aBlElement childrenCount = 0 ifTrue: [ ^ 0 ].
+	result := aBlElement childrenCount.
+	aBlElement childrenDo: [ :each | result := result + (self recursiveCountElementsIn: each) ].
+	^ result
+]
diff --git a/src/Pyramid-Bloc/PyramidNavigationTreePresenter.class.st b/src/Pyramid-Bloc/PyramidNavigationTreePresenter.class.st
index 5bab04d8..f37b41c2 100644
--- a/src/Pyramid-Bloc/PyramidNavigationTreePresenter.class.st
+++ b/src/Pyramid-Bloc/PyramidNavigationTreePresenter.class.st
@@ -5,7 +5,8 @@ Class {
 		'navigationModel',
 		'treeTable',
 		'editor',
-		'shouldUpdateSelection'
+		'shouldUpdateSelection',
+		'previousNumberOfElement'
 	],
 	#category : #'Pyramid-Bloc-plugin-navigation'
 }
@@ -127,6 +128,18 @@ PyramidNavigationTreePresenter >> navigationModel: anObject [
 		self treeTable expandAll ]
 ]
 
+{ #category : #accessing }
+PyramidNavigationTreePresenter >> previousNumberOfElement [
+
+	^ previousNumberOfElement
+]
+
+{ #category : #accessing }
+PyramidNavigationTreePresenter >> previousNumberOfElement: anObject [
+
+	previousNumberOfElement := anObject
+]
+
 { #category : #api }
 PyramidNavigationTreePresenter >> roots: aCollection [
 
@@ -154,14 +167,23 @@ PyramidNavigationTreePresenter >> treeTable [
 { #category : #'as yet unclassified' }
 PyramidNavigationTreePresenter >> updateRoots [
 
-	| currentTreeRoots roots parent shouldOrder |
+	| currentTreeRoots roots parent shouldOrder calculatedNumberOfElement |
 	self shouldUpdateSelection: false.
 
 	roots := self editor projectModel firstLevelElements asArray.
 	currentTreeRoots := self treeTable roots.
-	
-	(roots size = currentTreeRoots size and: [ roots includesAll: currentTreeRoots ] )ifTrue: [ self shouldUpdateSelection: true. ^ self ].
-	
+
+	(roots size = currentTreeRoots size and: [
+		 (roots includesAll: currentTreeRoots) and: [
+			 calculatedNumberOfElement := self editor projectModel
+				                              numberOfElements.
+			 calculatedNumberOfElement = self previousNumberOfElement ] ])
+		ifTrue: [
+			self shouldUpdateSelection: true.
+			^ self ].
+
+	self previousNumberOfElement: calculatedNumberOfElement.
+
 	parent := nil.
 
 	"If roots all have the same parent then it should be ordered by the parent children order."
diff --git a/src/Pyramid-Bloc/PyramidProjectModel.extension.st b/src/Pyramid-Bloc/PyramidProjectModel.extension.st
index b4728115..c337776f 100644
--- a/src/Pyramid-Bloc/PyramidProjectModel.extension.st
+++ b/src/Pyramid-Bloc/PyramidProjectModel.extension.st
@@ -6,3 +6,10 @@ PyramidProjectModel >> allElements [
 	^ PyramidElementsManipulationHelper flattenChildrenOfCollection:
 		  self firstLevelElements
 ]
+
+{ #category : #'*Pyramid-Bloc' }
+PyramidProjectModel >> numberOfElements [
+
+	^ PyramidElementsManipulationHelper countElementsIn:
+		  self firstLevelElements.
+]
diff --git a/src/Pyramid-Tests/PyramidElementsManipulationHelperTest.class.st b/src/Pyramid-Tests/PyramidElementsManipulationHelperTest.class.st
index 691ca691..f5dd54cf 100644
--- a/src/Pyramid-Tests/PyramidElementsManipulationHelperTest.class.st
+++ b/src/Pyramid-Tests/PyramidElementsManipulationHelperTest.class.st
@@ -38,6 +38,42 @@ D1 -> D2 -> D3.
 
 ]
 
+{ #category : #'as yet unclassified' }
+PyramidElementsManipulationHelperTest >> makeNestedElement: aNumber [
+
+	| origin current |
+	origin := current := BlElement new.
+	2 to: aNumber do: [ :i |
+		| temp |
+		temp := BlElement new.
+		current addChild: temp.
+		current := temp ].
+	^ origin
+]
+
+{ #category : #tests }
+PyramidElementsManipulationHelperTest >> testCountElement [
+	"selection := {A1 . B1 . B2 . C1 . C3}.
+	PyramidElementsManipulationHelper onlyParents: selection
+	returns: { A1 . B1 . C1 }"
+
+	self
+		assert: (PyramidElementsManipulationHelper countElementsIn: {  })
+		equals: 0.
+	self
+		assert: (PyramidElementsManipulationHelper countElementsIn:
+				 { (self makeNestedElement: 1) })
+		equals: 1.
+	self
+		assert: (PyramidElementsManipulationHelper countElementsIn:
+				 { (self makeNestedElement: 10) })
+		equals: 10.
+	self
+		assert: (PyramidElementsManipulationHelper countElementsIn:
+				 { (self makeNestedElement: 10) . (self makeNestedElement: 10) . (self makeNestedElement: 10) })
+		equals: 30
+]
+
 { #category : #tests }
 PyramidElementsManipulationHelperTest >> testFlattenChildrenOfCollection [
 
diff --git a/src/Pyramid/PyramidProjectModel.class.st b/src/Pyramid/PyramidProjectModel.class.st
index 1d53fa03..4cb9ccf6 100644
--- a/src/Pyramid/PyramidProjectModel.class.st
+++ b/src/Pyramid/PyramidProjectModel.class.st
@@ -42,10 +42,10 @@ PyramidProjectModel >> firstLevelElements [
 { #category : #'as yet unclassified' }
 PyramidProjectModel >> informElementsChanged [
 
-		self announce: (PyramidElementsChangedEvent new
-				 firstLevelElements: self firstLevelElements;
-				 selection: self selection;
-				 yourself)
+	self announce: (PyramidElementsChangedEvent new
+			 firstLevelElements: self firstLevelElements;
+			 selection: self selection;
+			 yourself)
 ]
 
 { #category : #'as yet unclassified' }