diff --git a/src/Spec2-Core/SpPresenterSelectorPresenter.class.st b/src/Spec2-Core/SpPresenterSelectorPresenter.class.st
index 1164cf98..e4f2446c 100644
--- a/src/Spec2-Core/SpPresenterSelectorPresenter.class.st
+++ b/src/Spec2-Core/SpPresenterSelectorPresenter.class.st
@@ -23,12 +23,6 @@ Class {
 	#tag : 'Widgets'
 }
 
-{ #category : 'transmission' }
-SpPresenterSelectorPresenter >> defaultInputPort [
-
-	^ self inputModelPort
-]
-
 { #category : 'api - focus' }
 SpPresenterSelectorPresenter >> defaultKeyboardFocus [
 
@@ -56,12 +50,6 @@ SpPresenterSelectorPresenter >> initializePresenters [
 	layout := SpBoxLayout newTopToBottom
 ]
 
-{ #category : 'transmission' }
-SpPresenterSelectorPresenter >> inputModelPort [
-
-	^ SpModelPort newPresenter: self
-]
-
 { #category : 'accessing - model' }
 SpPresenterSelectorPresenter >> setModel: anObject [
 
diff --git a/src/Spec2-Core/SpTModel.trait.st b/src/Spec2-Core/SpTModel.trait.st
index 83077295..708f8e5a 100644
--- a/src/Spec2-Core/SpTModel.trait.st
+++ b/src/Spec2-Core/SpTModel.trait.st
@@ -11,18 +11,6 @@ Trait {
 	#tag : 'Widgets'
 }
 
-{ #category : 'transmission' }
-SpTModel >> defaultInputPort [
-
-	^ self inputModelPort
-]
-
-{ #category : 'transmission' }
-SpTModel >> inputModelPort [
-
-	^ SpModelPort newPresenter: self
-]
-
 { #category : 'accessing - model' }
 SpTModel >> model [
 
diff --git a/src/Spec2-Transmission/SpPresenterSelectorPresenter.extension.st b/src/Spec2-Transmission/SpPresenterSelectorPresenter.extension.st
new file mode 100644
index 00000000..e775731f
--- /dev/null
+++ b/src/Spec2-Transmission/SpPresenterSelectorPresenter.extension.st
@@ -0,0 +1,13 @@
+Extension { #name : 'SpPresenterSelectorPresenter' }
+
+{ #category : '*Spec2-Transmission' }
+SpPresenterSelectorPresenter >> defaultInputPort [
+
+	^ self inputModelPort
+]
+
+{ #category : '*Spec2-Transmission' }
+SpPresenterSelectorPresenter >> inputModelPort [
+
+	^ SpModelPort newPresenter: self
+]
diff --git a/src/Spec2-Transmission/SpTModel.extension.st b/src/Spec2-Transmission/SpTModel.extension.st
new file mode 100644
index 00000000..ead14d4d
--- /dev/null
+++ b/src/Spec2-Transmission/SpTModel.extension.st
@@ -0,0 +1,13 @@
+Extension { #name : 'SpTModel' }
+
+{ #category : '*Spec2-Transmission' }
+SpTModel >> defaultInputPort [
+
+	^ self inputModelPort
+]
+
+{ #category : '*Spec2-Transmission' }
+SpTModel >> inputModelPort [
+
+	^ SpModelPort newPresenter: self
+]