diff --git a/src/Pyramid-Bloc/PyramidAbstractColumnsBuilder.class.st b/src/Pyramid-Bloc/PyramidAbstractColumnsBuilder.class.st
new file mode 100644
index 00000000..afe4b59d
--- /dev/null
+++ b/src/Pyramid-Bloc/PyramidAbstractColumnsBuilder.class.st
@@ -0,0 +1,34 @@
+Class {
+	#name : #PyramidAbstractColumnsBuilder,
+	#superclass : #Object,
+	#instVars : [
+		'editor'
+	],
+	#category : #'Pyramid-Bloc-plugin-tree-library'
+}
+
+{ #category : #testing }
+PyramidAbstractColumnsBuilder class >> isAbstract [
+
+	^ self == PyramidAbstractColumnsBuilder
+]
+
+{ #category : #'as yet unclassified' }
+PyramidAbstractColumnsBuilder >> buildOn: aPyramidTreePlugin [
+"aPyramidTreePlugin addColumns: {  }"
+	self shouldBeImplemented
+	
+]
+
+{ #category : #accessing }
+PyramidAbstractColumnsBuilder >> editor [
+
+	editor ifNil: [ Error signal: 'Editor should not be nil.' ].
+	^ editor
+]
+
+{ #category : #accessing }
+PyramidAbstractColumnsBuilder >> editor: anObject [
+
+	editor := anObject
+]
diff --git a/src/Pyramid-Bloc/PyramidLibraryPresenter.class.st b/src/Pyramid-Bloc/PyramidLibraryPresenter.class.st
index 8f10d4d4..0ca3a40e 100644
--- a/src/Pyramid-Bloc/PyramidLibraryPresenter.class.st
+++ b/src/Pyramid-Bloc/PyramidLibraryPresenter.class.st
@@ -8,23 +8,26 @@ Class {
 		'addButton',
 		'idGenerator'
 	],
+	#classVars : [
+		'IdGenerator'
+	],
 	#category : #'Pyramid-Bloc-plugin-tree-library'
 }
 
 { #category : #accessing }
-PyramidLibraryPresenter class >> idGenerator [
+PyramidLibraryPresenter class >> makeIdGenerator [
 ^ Generator on: [ :generator |
-		               | index |
-		               index := 1.
-		               [
-		               Character alphabet do: [ :each |
-			               | next suffix |
-			               next := each asUppercase asString.
-			               suffix := index = 1
-				                         ifTrue: [ '' ]
-				                         ifFalse: [ index asString ].
-			               generator yield: next , suffix ].
-		               index := index + 1 ] repeat ].
+		  | index |
+		  index := 1.
+		  [
+		  Character alphabet do: [ :each |
+			  | next suffix |
+			  next := each asUppercase asString.
+			  suffix := index = 1
+				            ifTrue: [ '' ]
+				            ifFalse: [ index asString ].
+			  generator yield: next , suffix ].
+		  index := index + 1 ] repeat ]
 ]
 
 { #category : #initialization }
@@ -92,7 +95,7 @@ PyramidLibraryPresenter >> defaultLayout [
 						    expand: false;
 						    yourself)
 				   width: 300;
-				   yourself)
+				   yourself); yourself
 ]
 
 { #category : #accessing }
@@ -109,6 +112,7 @@ PyramidLibraryPresenter >> editor: aPyramidEditor [
 { #category : #accessing }
 PyramidLibraryPresenter >> idGenerator [
 
+	idGenerator ifNil: [ idGenerator := self class makeIdGenerator ].
 	^ idGenerator
 ]
 
@@ -121,8 +125,6 @@ PyramidLibraryPresenter >> idGenerator: anObject [
 { #category : #initialization }
 PyramidLibraryPresenter >> initializePresenters [
 
-	idGenerator := self class idGenerator.
-
 	addButton := SpButtonPresenter new
 		             label: self buttonLabel;
 		             action: [ self buttonAction ];
diff --git a/src/Pyramid-Bloc/PyramidPluginTestModeTest.class.st b/src/Pyramid-Bloc/PyramidPluginTestModeTest.class.st
new file mode 100644
index 00000000..640a965e
--- /dev/null
+++ b/src/Pyramid-Bloc/PyramidPluginTestModeTest.class.st
@@ -0,0 +1,81 @@
+Class {
+	#name : #PyramidPluginTestModeTest,
+	#superclass : #TestCase,
+	#instVars : [
+		'plugin',
+		'spacePlugin',
+		'editor'
+	],
+	#category : #'Pyramid-Bloc-plugin-testmode'
+}
+
+{ #category : #accessing }
+PyramidPluginTestModeTest >> editor [
+^ editor
+]
+
+{ #category : #accessing }
+PyramidPluginTestModeTest >> plugin [
+
+	^ plugin
+]
+
+{ #category : #running }
+PyramidPluginTestModeTest >> setUp [
+
+	super setUp.
+
+	plugin := PyramidPluginTestMode new.
+	spacePlugin := PyramidSpacePlugin new.
+	editor := PyramidEditorBuilder new plugins: { plugin . spacePlugin }; build.
+]
+
+{ #category : #tests }
+PyramidPluginTestModeTest >> testIsTestOnGoing [
+
+	self assert: self plugin isTestOnGoing not.
+	self plugin switchToTestMode.
+	self assert: self plugin isTestOnGoing.
+	self plugin switchToTestMode.
+	self assert: self plugin isTestOnGoing not.
+]
+
+{ #category : #tests }
+PyramidPluginTestModeTest >> testSwitchToTestMode [
+
+	| element elementThatReceiveEvent |
+	element := BlElement new
+		           size: 500 asPoint;
+		           background: Color blue;
+		           addEventHandler: (BlEventHandler
+				            on: BlPrimaryClickEvent
+				            do: [ :evt |  ]);
+		           yourself.
+	self plugin elementAtEvents addEventHandler: (BlEventHandler
+			 on: BlPrimaryClickEvent
+			 do: [ :evt |  ]).
+	self editor projectModel firstLevelElements add: element.
+
+	self plugin elementAtMain forceLayout.
+	elementThatReceiveEvent := self plugin elementAtMain
+		                           findMouseEventTargetAt:
+		                           10 asPoint
+		                           + self plugin currentTransformTranslation.
+	self deny: elementThatReceiveEvent equals: element.
+
+	self plugin switchToTestMode.
+	self plugin elementAtMain forceLayout.
+	elementThatReceiveEvent := self plugin elementAtMain
+		                           findMouseEventTargetAt:
+		                           10 asPoint
+		                           + self plugin currentTransformTranslation.
+	self assert: elementThatReceiveEvent equals: element.
+
+	self plugin switchToTestMode.
+	self plugin elementAtMain forceLayout.
+	elementThatReceiveEvent := self plugin elementAtMain
+		                           findMouseEventTargetAt:
+		                           10 asPoint
+		                           + self plugin currentTransformTranslation.
+	self deny: elementThatReceiveEvent equals: element
+]
diff --git a/src/Pyramid-Bloc/PyramidTreeBaseColumnsBuilder.class.st b/src/Pyramid-Bloc/PyramidTreeBaseColumnsBuilder.class.st
new file mode 100644
index 00000000..ed894e52
--- /dev/null
+++ b/src/Pyramid-Bloc/PyramidTreeBaseColumnsBuilder.class.st
@@ -0,0 +1,94 @@
+Class {
+	#name : #PyramidTreeBaseColumnsBuilder,
+	#superclass : #PyramidAbstractColumnsBuilder,
+	#category : #'Pyramid-Bloc-plugin-tree-library'
+}
+
+{ #category : #'as yet unclassified' }
+PyramidTreeBaseColumnsBuilder >> buildOn: aPyramidTreePlugin [
+
+	aPyramidTreePlugin addColumns: { self nameAndTypeColumn . self hashColumn . self zIndexColumn . self visibilityColumn  }
+]
+
+{ #category : #accessing }
+PyramidTreeBaseColumnsBuilder >> hashColumn [
+
+	^ SpStringTableColumn new
+			              title: 'Hash';
+			              evaluated: [ :aBlElement |
+				              aBlElement identityHash printString ];
+			              displayColor: [ :aBlElement | Color gray ];
+			              width: 60;
+			              yourself
+]
+
+{ #category : #accessing }
+PyramidTreeBaseColumnsBuilder >> nameAndTypeColumn [
+
+	^ SpCompositeTableColumn new
+		  title: 'Elements';
+		  addColumn:
+			  (SpImageTableColumn evaluated: [ :aBlElement | aBlElement asIcon ]);
+		  addColumn: (SpStringTableColumn new
+				   title: 'Identifier';
+				   evaluated: [ :aBlElement |
+					   aBlElement elementId isNoId
+						   ifTrue: [ '@\no name\' ]
+						   ifFalse: [ aBlElement id asSymbol ] ];
+				   yourself);
+		  addColumn: (SpStringTableColumn new
+				   title: 'Class';
+				   evaluated: [ :aBlElement | aBlElement class name ];
+				   displayColor: [ :aBlElement | Color gray ];
+				   displayItalic: [ :aBlElement | true ];
+				   yourself);
+		  yourself
+]
+
+{ #category : #initialization }
+PyramidTreeBaseColumnsBuilder >> setVisibility: aBlVisibility of: aBlElement onEditor: aPyramidEditor [
+
+	aPyramidEditor propertiesManager commandExecutor
+		use: PyramidVisibilityCommand new
+		on: { aBlElement }
+		with: aBlVisibility
+]
+
+{ #category : #accessing }
+PyramidTreeBaseColumnsBuilder >> visibilityColumn [
+
+	^ SpCompositeTableColumn new
+		  title: 'Visibility';
+		  width: 80;
+		  addColumn: (SpImageTableColumn evaluated: [ :aBlElement |
+					   aBlElement
+						   allParentsDetect: [ :parent | parent isVisible not ]
+						   ifFound: [ :parent | self iconNamed: #uncommentedClass ]
+						   ifNone: [ self iconNamed: #blank16 ] ]);
+		  addColumn: (SpImageTableColumn evaluated: [ :aBlElement |
+					   aBlElement visibility asIcon ]);
+		  addColumn: (SpLinkTableColumn new
+				   title: 'Visible';
+				   url: [ :aBlElement | '' ];
+				   action: [ :aBlElement |
+					   self
+						   setVisibility: aBlElement visibility nextVisibilityForTree
+						   of: aBlElement
+						   onEditor: self editor ];
+				   evaluated: [ :aBlElement | aBlElement visibility asString ];
+				   yourself);
+		  yourself
+]
+
+{ #category : #accessing }
+PyramidTreeBaseColumnsBuilder >> zIndexColumn [
+
+	^ SpStringTableColumn new
+		  title: 'z';
+		  evaluated: [ :aBlElement |
+			  aBlElement elevation elevation = 0
+				  ifTrue: [ '' ]
+				  ifFalse: [ aBlElement elevation elevation printString ] ];
+		  width: 16;
+		  yourself
+]
diff --git a/src/Pyramid-Bloc/PyramidTreePlugin.class.st b/src/Pyramid-Bloc/PyramidTreePlugin.class.st
index 1375c546..b6c0ee2b 100644
--- a/src/Pyramid-Bloc/PyramidTreePlugin.class.st
+++ b/src/Pyramid-Bloc/PyramidTreePlugin.class.st
@@ -9,89 +9,33 @@ Class {
 		'libraryPresenterForElement',
 		'libraryPresenterForRoot'
 	],
+	#classVars : [
+		'ColumnsBuildersClasses'
+	],
 	#category : #'Pyramid-Bloc-plugin-tree-library'
 }
 
-{ #category : #'as yet unclassified' }
-PyramidTreePlugin class >> columnHashValue: aPyramidTreePlugin [
-
-	^ SpStringTableColumn new
-		  title: 'Hash';
-		  evaluated: [ :aBlElement | aBlElement identityHash printString ];
-		  displayColor: [ :aBlElement | Color gray ];
-		  width: 60;
-		  yourself
-]
+{ #category : #accessing }
+PyramidTreePlugin class >> columnsBuildersClasses [
 
-{ #category : #'as yet unclassified' }
-PyramidTreePlugin class >> columnNameAndType: aPyramidTreePlugin [
-
-	^ SpCompositeTableColumn new
-		  title: 'Elements';
-		  addColumn:
-			  (SpImageTableColumn evaluated: [ :aBlElement | aBlElement asIcon ]);
-		  addColumn: (SpStringTableColumn new
-				   title: 'Identifier';
-				   evaluated: [ :aBlElement |
-					   aBlElement elementId isNoId
-						   ifTrue: [ '@\no name\' ]
-						   ifFalse: [ aBlElement id asSymbol ] ];
-				   yourself);
-		  addColumn: (SpStringTableColumn new
-				   title: 'Class';
-				   evaluated: [ :aBlElement | aBlElement class name ];
-				   displayColor: [ :aBlElement | Color gray ];
-				   displayItalic: [ :aBlElement | true ];
-				   yourself);
-		  yourself
+	ColumnsBuildersClasses ifNil: [
+		ColumnsBuildersClasses := Set new ].
+	^ ColumnsBuildersClasses
 ]
 
-{ #category : #'as yet unclassified' }
-PyramidTreePlugin class >> columnVisibility: aPyramidTreePlugin [
-
-	^ SpCompositeTableColumn new
-		  title: 'Visibility';
-		  width: 80;
-		  addColumn: (SpImageTableColumn evaluated: [ :aBlElement |
-					   aBlElement
-						   allParentsDetect: [ :parent | parent isVisible not ]
-						   ifFound: [ :parent | self iconNamed: #uncommentedClass ]
-						   ifNone: [ self iconNamed: #blank16 ] ]);
-		  addColumn: (SpImageTableColumn evaluated: [ :aBlElement |
-					   aBlElement visibility asIcon ]);
-		  addColumn: (SpLinkTableColumn new
-				   title: 'Visible';
-				   url: [ :aBlElement | '' ];
-				   action: [ :aBlElement |
-					   self
-						   setVisibility: aBlElement visibility nextVisibilityForTree
-						   of: aBlElement
-						   onEditor: aPyramidTreePlugin editor ];
-				   evaluated: [ :aBlElement | aBlElement visibility asString ];
-				   yourself);
-		  yourself
-]
+{ #category : #initialization }
+PyramidTreePlugin class >> install [
+	"Do some stuff here when the plugin used class oriented behavior"
 
-{ #category : #'as yet unclassified' }
-PyramidTreePlugin class >> columnZIndex: aPyramidTreePlugin [
-
-	^ SpStringTableColumn new
-		  title: 'z';
-		  evaluated: [ :aBlElement |
-			  aBlElement elevation elevation = 0
-				  ifTrue: [ '' ]
-				  ifFalse: [ aBlElement elevation elevation printString ] ];
-		  width: 16;
-		  yourself
+	self columnsBuildersClasses add: PyramidTreeBaseColumnsBuilder 
 ]
 
 { #category : #initialization }
-PyramidTreePlugin class >> setVisibility: aBlVisibility of: aBlElement onEditor: aPyramidEditor [
+PyramidTreePlugin >> addColumns: aCollection [
+	aCollection do: [ :each | self treePresenter columns add: each ].
+	self treePresenter updateTree
 
-	aPyramidEditor propertiesManager commandExecutor
-		use: PyramidVisibilityCommand new
-		on: { aBlElement }
-		with: aBlVisibility
+	
 ]
 
 { #category : #adding }
@@ -109,13 +53,19 @@ PyramidTreePlugin >> addPanelsOn: aPyramidSimpleWindow [
 		addItem: [ :builder | self menuAddAndDeleteOn: builder ]
 ]
 
+{ #category : #actions }
+PyramidTreePlugin >> configureBuilder: aPyramidEditorBuilder [
+
+	self class columnsBuildersClasses do: [ :each |
+		each new
+			editor: aPyramidEditorBuilder editor;
+			buildOn: self ]
+]
+
 { #category : #connecting }
 PyramidTreePlugin >> connectOn: aPyramidEditor [
 
 	self editor: aPyramidEditor.
-	self treePresenter projectModel: aPyramidEditor projectModel.
-	self treePresenter editorMenuBuilder:
-		(self editor window services at: #selectionMenu) builder
 ]
 
 { #category : #accessing }
@@ -125,11 +75,14 @@ PyramidTreePlugin >> editor [
 ]
 
 { #category : #accessing }
-PyramidTreePlugin >> editor: anObject [
+PyramidTreePlugin >> editor: aPyramidEditor [
 
-	editor := anObject.
-	self libraryPresenterForElement editor: anObject.
-	self libraryPresenterForRoot editor: anObject.
+	editor := aPyramidEditor.
+	self libraryPresenterForElement editor: aPyramidEditor.
+	self libraryPresenterForRoot editor: aPyramidEditor.
+	self treePresenter projectModel: aPyramidEditor projectModel.
+	self treePresenter editorMenuBuilder:
+		(self editor window services at: #selectionMenu) builder
 ]
 
 { #category : #initialization }
@@ -139,35 +92,25 @@ PyramidTreePlugin >> initialize [
 	treePresenter := PyramidTreePresenter new
 		                 libraryPresenterForRoot:
 			                 self libraryPresenterForRoot;
-		                 yourself.
-	self initializeTreeColumns.
+		                 yourself
 ]
 
 { #category : #initialization }
 PyramidTreePlugin >> initializeLibraryPresenters [
 
 	| idGenerator |
-	idGenerator :=  PyramidLibraryPresenter idGenerator.
+	idGenerator := PyramidLibraryPresenter makeIdGenerator.
 	libraryPresenterForElement := PyramidLibraryPresenterForElement new
 		                              editor: self editor;
-		idGenerator: idGenerator;
+		                              idGenerator: idGenerator;
 		                              yourself.
-	libraryPresenterForRoot := PyramidLibraryPresenterForFirstLevelElement new
+	libraryPresenterForRoot := PyramidLibraryPresenterForFirstLevelElement
+		                           new
 		                           editor: self editor;
-		idGenerator: idGenerator;
+		                           idGenerator: idGenerator;
 		                           yourself
 ]
 
-{ #category : #initialization }
-PyramidTreePlugin >> initializeTreeColumns [
-
-	self treePresenter columns add: (self class columnNameAndType: self).
-	self treePresenter columns add: (self class columnHashValue: self).
-	self treePresenter columns add: (self class columnZIndex: self).
-	self treePresenter columns add: (self class columnVisibility: self).
-	self treePresenter updateTree
-]
-
 { #category : #'as yet unclassified' }
 PyramidTreePlugin >> libraryPresenterForElement [
 
diff --git a/src/Pyramid-Tests/PyramidLibraryPresenterTest.class.st b/src/Pyramid-Tests/PyramidLibraryPresenterTest.class.st
new file mode 100644
index 00000000..eb97f74f
--- /dev/null
+++ b/src/Pyramid-Tests/PyramidLibraryPresenterTest.class.st
@@ -0,0 +1,26 @@
+Class {
+	#name : #PyramidLibraryPresenterTest,
+	#superclass : #TestCase,
+	#category : #'Pyramid-Tests-cases-plugin-tree-library'
+}
+
+{ #category : #tests }
+PyramidLibraryPresenterTest >> testIdGenerator [
+	"We generate a bunch of id and we verify that none are the same"
+
+	| treePlugin libraryPresForElements libraryPresForFirstLevel elements |
+	treePlugin := PyramidTreePlugin new.
+	libraryPresForElements := treePlugin libraryPresenterForElement.
+	libraryPresForFirstLevel := treePlugin libraryPresenterForRoot.
+	elements := Bag new.
+	1 to: 100 do: [ :i |
+		elements add:
+			libraryPresForElements list selectedItem blockMaker value id
+				asSymbol ].
+	1 to: 100 do: [ :i |
+		elements add:
+			libraryPresForFirstLevel list selectedItem blockMaker value id
+				asSymbol ].
+	self assert: elements size equals: 200.
+	self assert: elements asSet size equals: 200
+]
diff --git a/src/Pyramid/PyramidSpCodeObjectInteractionModel.class.st b/src/Pyramid-Tests/PyramidSpCodeObjectInteractionModel.class.st
similarity index 95%
rename from src/Pyramid/PyramidSpCodeObjectInteractionModel.class.st
rename to src/Pyramid-Tests/PyramidSpCodeObjectInteractionModel.class.st
index 1e6bd904..c62298b3 100644
--- a/src/Pyramid/PyramidSpCodeObjectInteractionModel.class.st
+++ b/src/Pyramid-Tests/PyramidSpCodeObjectInteractionModel.class.st
@@ -4,7 +4,7 @@ Class {
 	#instVars : [
 		'projectModel'
 	],
-	#category : #'Pyramid-plugin-selection'
+	#category : #'Pyramid-Tests-cases-plugin-playground'
 }
 
 { #category : #accessing }
diff --git a/src/Pyramid-Tests/PyramidSpCodeObjectInteractionModelTest.class.st b/src/Pyramid-Tests/PyramidSpCodeObjectInteractionModelTest.class.st
new file mode 100644
index 00000000..3f33af93
--- /dev/null
+++ b/src/Pyramid-Tests/PyramidSpCodeObjectInteractionModelTest.class.st
@@ -0,0 +1,85 @@
+Class {
+	#name : #PyramidSpCodeObjectInteractionModelTest,
+	#superclass : #TestCase,
+	#instVars : [
+		'projectModel',
+		'interactionModel',
+		'firstLevelElements'
+	],
+	#category : #'Pyramid-Tests-cases-plugin-playground'
+}
+
+{ #category : #running }
+PyramidSpCodeObjectInteractionModelTest >> firstLevelElements [
+
+	^ firstLevelElements
+]
+
+{ #category : #running }
+PyramidSpCodeObjectInteractionModelTest >> interactionModel [
+
+	^ interactionModel
+]
+
+{ #category : #running }
+PyramidSpCodeObjectInteractionModelTest >> projectModel [
+	^ projectModel
+]
+
+{ #category : #running }
+PyramidSpCodeObjectInteractionModelTest >> setUp [
+
+	super setUp.
+
+	firstLevelElements := Object new.
+	projectModel := PyramidProjectModel new.
+	projectModel firstLevelElements add: firstLevelElements.
+
+	interactionModel := PyramidSpCodeObjectInteractionModel new
+		                    projectModel: projectModel;
+		                    yourself
+]
+
+{ #category : #tests }
+PyramidSpCodeObjectInteractionModelTest >> testDoItReceiver [
+
+	| obj1 obj2 |
+	obj1 := Object new.
+	obj2 := Object new.
+	self projectModel setSelection: #(  ).
+	self assert: (interactionModel doItReceiver isKindOf: Collection).
+	self assert: interactionModel doItReceiver size equals: 1.
+	self assert:
+		(interactionModel doItReceiver includes: self firstLevelElements).
+
+	self projectModel setSelection: { obj1 }.
+	self assert: interactionModel doItReceiver equals: obj1.
+
+	self projectModel setSelection: {
+			obj1.
+			obj2 }.
+	self assert: (interactionModel doItReceiver isKindOf: Collection).
+	self assert: interactionModel doItReceiver size equals: 2.
+	self assert: (interactionModel doItReceiver includes: obj1).
+	self assert: (interactionModel doItReceiver includes: obj2)
+]
+
+{ #category : #tests }
+PyramidSpCodeObjectInteractionModelTest >> testDoItReceiverString [
+
+	self projectModel setSelection: #(  ).
+	self
+		assert: interactionModel doItReceiverString
+		equals: 'the collection of first level elements'.
+
+	self projectModel setSelection: { 1 }.
+	self
+		assert: interactionModel doItReceiverString
+		equals: 'the selected element'.
+
+	self projectModel setSelection: { 1. 2 }.
+	self assert: interactionModel doItReceiverString equals: 'an array of 2 selected elements'.
+
+	self projectModel setSelection: { 1. 2. 3. 4. 5 }.
+	self assert: interactionModel doItReceiverString equals: 'an array of 5 selected elements'
+]
diff --git a/src/Pyramid-Tests/PyramidTreePluginTest.class.st b/src/Pyramid-Tests/PyramidTreePluginTest.class.st
new file mode 100644
index 00000000..3ac7ded7
--- /dev/null
+++ b/src/Pyramid-Tests/PyramidTreePluginTest.class.st
@@ -0,0 +1,50 @@
+Class {
+	#name : #PyramidTreePluginTest,
+	#superclass : #TestCase,
+	#category : #'Pyramid-Tests-cases-plugin-tree-library'
+}
+
+{ #category : #tests }
+PyramidTreePluginTest >> testAddColumns [
+
+	| plugin |
+	plugin := PyramidTreePlugin new.
+	self assert: plugin treePresenter columns size equals: 0.
+	plugin addColumns: { SpStringTableColumn new
+		  title: 'Test1';
+		  yourself. SpStringTableColumn new
+		  title: 'Test2';
+		  yourself. SpStringTableColumn new
+		  title: 'Test3';
+		  yourself }.
+	self assert: plugin treePresenter columns size equals: 3.
+]
+
+{ #category : #tests }
+PyramidTreePluginTest >> testRemoveSelectedElements [
+
+	| plugin editor e1 e2 e3 |
+	e1 := BlElement new.
+	e2 := BlElement new.
+	e3 := BlElement new.
+	editor := PyramidEditor new.
+	editor window: PyramidSimpleWindow new.
+	plugin := PyramidTreePlugin new.
+	plugin editor: editor.
+	editor projectModel addObserver: plugin treePresenter.
+	editor projectModel firstLevelElements addAll: {
+			e1.
+			e2.
+			e3 }.
+	editor projectModel setSelection: {
+			e1.
+			e2 }.
+	self assert: plugin treePresenter tree selectedItems size equals: 2.
+	self assert: (plugin treePresenter tree selectedItems includes: e1).
+	self assert: (plugin treePresenter tree selectedItems includes: e2).
+	plugin removeSelectedElements.
+	self assert: plugin treePresenter tree selectedItems size equals: 0.
+	self assert: editor projectModel selection size equals: 0.
+	self assert: editor projectModel firstLevelElements size equals: 1.
+	self assert: editor projectModel firstLevelElements first equals: e3.
+]
diff --git a/src/Pyramid/PyramidSelectionView.class.st b/src/Pyramid/PyramidPlaygroundView.class.st
similarity index 65%
rename from src/Pyramid/PyramidSelectionView.class.st
rename to src/Pyramid/PyramidPlaygroundView.class.st
index 380b9162..bbbb9dba 100644
--- a/src/Pyramid/PyramidSelectionView.class.st
+++ b/src/Pyramid/PyramidPlaygroundView.class.st
@@ -1,5 +1,5 @@
 Class {
-	#name : #PyramidSelectionView,
+	#name : #PyramidPlaygroundView,
 	#superclass : #SpPresenter,
 	#traits : 'TPyramidProjectModelObserver',
 	#classTraits : 'TPyramidProjectModelObserver classTrait',
@@ -10,23 +10,23 @@ Class {
 		'codeObjectInteractionModel',
 		'contextLabel'
 	],
-	#category : #'Pyramid-plugin-selection'
+	#category : #'Pyramid-plugin-playground'
 }
 
 { #category : #accessing }
-PyramidSelectionView >> contextLabel [
+PyramidPlaygroundView >> contextLabel [
 
 	^ contextLabel
 ]
 
 { #category : #'as yet unclassified' }
-PyramidSelectionView >> currentSelection [
+PyramidPlaygroundView >> currentSelection [
 
 	^ self projectModel selection
 ]
 
 { #category : #layout }
-PyramidSelectionView >> defaultLayout [
+PyramidPlaygroundView >> defaultLayout [
 
 	^ SpPanedLayout newVertical
 		  add: (SpBoxLayout newVertical
@@ -48,48 +48,53 @@ PyramidSelectionView >> defaultLayout [
 ]
 
 { #category : #initialization }
-PyramidSelectionView >> initializePresenters [
+PyramidPlaygroundView >> initializePresenters [
 
 	list := SpListPresenter new.
-	playground := PyramidSpCodePresenter new.
+	playground := SpCodePresenter new.
 	contextLabel := SpLabelPresenter new.
+
+	playground interactionModel: PyramidSpCodeObjectInteractionModel new.
+	playground announcer
+		when: SpCodeEvaluationSucceedAnnouncement
+		do: [ :ann | self projectModel informElementsChanged ]
 ]
 
 { #category : #accessing }
-PyramidSelectionView >> list [
+PyramidPlaygroundView >> list [
 ^ list
 ]
 
 { #category : #accessing }
-PyramidSelectionView >> playground [
+PyramidPlaygroundView >> playground [
 	^ playground
 ]
 
 { #category : #accessing }
-PyramidSelectionView >> projectModel [
+PyramidPlaygroundView >> projectModel [
 
 	^ projectModel
 ]
 
 { #category : #accessing }
-PyramidSelectionView >> projectModel: aPyramidActiveProject [
+PyramidPlaygroundView >> projectModel: aPyramidActiveProject [
 
 	projectModel := aPyramidActiveProject.
 	projectModel addObserver: self.
-	self playground projectModel: aPyramidActiveProject.
+	self playground interactionModel projectModel: aPyramidActiveProject.
 	
 		self pyramidSelectionChanged.
 ]
 
 { #category : #'as yet unclassified' }
-PyramidSelectionView >> pyramidSelectionChanged [
+PyramidPlaygroundView >> pyramidSelectionChanged [
 
 	self list items: self currentSelection.
 	contextLabel label: self valueOfSelf.
 ]
 
 { #category : #'as yet unclassified' }
-PyramidSelectionView >> valueOfSelf [
+PyramidPlaygroundView >> valueOfSelf [
 
 	^ 'self is <1s>' expandMacrosWith:
 		  self playground interactionModel doItReceiverString
diff --git a/src/Pyramid/PyramidPluginSelection.class.st b/src/Pyramid/PyramidPluginPlayground.class.st
similarity index 62%
rename from src/Pyramid/PyramidPluginSelection.class.st
rename to src/Pyramid/PyramidPluginPlayground.class.st
index 4b6ad465..9518fe54 100644
--- a/src/Pyramid/PyramidPluginSelection.class.st
+++ b/src/Pyramid/PyramidPluginPlayground.class.st
@@ -1,5 +1,5 @@
 Class {
-	#name : #PyramidPluginSelection,
+	#name : #PyramidPluginPlayground,
 	#superclass : #Object,
 	#traits : 'TPyramidPlugin',
 	#classTraits : 'TPyramidPlugin classTrait',
@@ -7,11 +7,11 @@ Class {
 		'activeProject',
 		'view'
 	],
-	#category : #'Pyramid-plugin-selection'
+	#category : #'Pyramid-plugin-playground'
 }
 
 { #category : #adding }
-PyramidPluginSelection >> addPanelsOn: aPyramidSimpleWindow [
+PyramidPluginPlayground >> addPanelsOn: aPyramidSimpleWindow [
 
 	aPyramidSimpleWindow at: #tabRight addItem: [ :builder |
 		builder
@@ -22,19 +22,19 @@ PyramidPluginSelection >> addPanelsOn: aPyramidSimpleWindow [
 ]
 
 { #category : #connecting }
-PyramidPluginSelection >> connectOn: aPyramidEditor [
+PyramidPluginPlayground >> connectOn: aPyramidEditor [
 
 	self view projectModel: aPyramidEditor projectModel
 ]
 
 { #category : #initialization }
-PyramidPluginSelection >> initialize [
+PyramidPluginPlayground >> initialize [
 
-	view := PyramidSelectionView new
+	view := PyramidPlaygroundView new
 ]
 
 { #category : #initialization }
-PyramidPluginSelection >> view [
+PyramidPluginPlayground >> view [
 
 	^ view
 ]
diff --git a/src/Pyramid/PyramidProjectModelObserverForTest.class.st b/src/Pyramid/PyramidProjectModelObserverForTest.class.st
new file mode 100644
index 00000000..71f13b43
--- /dev/null
+++ b/src/Pyramid/PyramidProjectModelObserverForTest.class.st
@@ -0,0 +1,73 @@
+Class {
+	#name : #PyramidProjectModelObserverForTest,
+	#superclass : #Object,
+	#traits : 'TPyramidProjectModelObserver',
+	#classTraits : 'TPyramidProjectModelObserver classTrait',
+	#instVars : [
+		'pyramidElementsChangedAction',
+		'pyramidFirstLevelElementsChangedAction',
+		'pyramidSelectionChangedAction'
+	],
+	#category : #'Pyramid-plugin-playground'
+}
+
+{ #category : #initialization }
+PyramidProjectModelObserverForTest >> initialize [ 
+
+	self pyramidElementsChangedAction: [  ].
+	self pyramidFirstLevelElementsChangedAction: [  ].self pyramidSelectionChangedAction: [  ]
+]
+
+{ #category : #'as yet unclassified' }
+PyramidProjectModelObserverForTest >> pyramidElementsChanged [
+
+	self pyramidElementsChangedAction value.
+]
+
+{ #category : #accessing }
+PyramidProjectModelObserverForTest >> pyramidElementsChangedAction [
+
+	^ pyramidElementsChangedAction
+]
+
+{ #category : #accessing }
+PyramidProjectModelObserverForTest >> pyramidElementsChangedAction: anObject [
+
+	pyramidElementsChangedAction := anObject
+]
+
+{ #category : #'as yet unclassified' }
+PyramidProjectModelObserverForTest >> pyramidFirstLevelElementsChanged [
+
+	self pyramidFirstLevelElementsChangedAction value
+]
+
+{ #category : #accessing }
+PyramidProjectModelObserverForTest >> pyramidFirstLevelElementsChangedAction [
+
+	^ pyramidFirstLevelElementsChangedAction
+]
+
+{ #category : #accessing }
+PyramidProjectModelObserverForTest >> pyramidFirstLevelElementsChangedAction: anObject [
+
+	pyramidFirstLevelElementsChangedAction := anObject
+]
+
+{ #category : #'as yet unclassified' }
+PyramidProjectModelObserverForTest >> pyramidSelectionChanged [
+
+	self pyramidSelectionChangedAction value
+]
+
+{ #category : #accessing }
+PyramidProjectModelObserverForTest >> pyramidSelectionChangedAction [
+
+	^ pyramidSelectionChangedAction
+]
+
+{ #category : #accessing }
+PyramidProjectModelObserverForTest >> pyramidSelectionChangedAction: anObject [
+
+	pyramidSelectionChangedAction := anObject
+]
diff --git a/src/Pyramid/PyramidSpCodePresenter.class.st b/src/Pyramid/PyramidSpCodePresenter.class.st
deleted file mode 100644
index e41ad189..00000000
--- a/src/Pyramid/PyramidSpCodePresenter.class.st
+++ /dev/null
@@ -1,36 +0,0 @@
-Class {
-	#name : #PyramidSpCodePresenter,
-	#superclass : #SpCodePresenter,
-	#category : #'Pyramid-plugin-selection'
-}
-
-{ #category : #'command support' }
-PyramidSpCodePresenter >> evaluate: aString onCompileError: compileErrorBlock onError: errorBlock [
-
-	| result |
-	result := super
-		          evaluate: aString
-		          onCompileError: compileErrorBlock
-		          onError: errorBlock.
-	self projectModel informElementsChanged.
-	^ result
-]
-
-{ #category : #accessing }
-PyramidSpCodePresenter >> initialize [
-
-	super initialize.
-	self interactionModel: PyramidSpCodeObjectInteractionModel new.
-]
-
-{ #category : #accessing }
-PyramidSpCodePresenter >> projectModel [
-
-	^ self interactionModel projectModel
-]
-
-{ #category : #accessing }
-PyramidSpCodePresenter >> projectModel: aPyramidActiveProject [
-
-	self interactionModel projectModel: aPyramidActiveProject
-]