diff --git a/src/Spec2-Adapters-Morphic/LayoutPolicy.extension.st b/src/Spec2-Adapters-Morphic/LayoutPolicy.extension.st
new file mode 100644
index 00000000..d7462c6c
--- /dev/null
+++ b/src/Spec2-Adapters-Morphic/LayoutPolicy.extension.st
@@ -0,0 +1,6 @@
+Extension { #name : 'LayoutPolicy' }
+
+{ #category : '*Spec2-Adapters-Morphic' }
+LayoutPolicy >> isFromEnd [
+	^ false
+]
diff --git a/src/Spec2-Adapters-Morphic/SpMorphicBackend.class.st b/src/Spec2-Adapters-Morphic/SpMorphicBackend.class.st
index 2a72f769..ac73d31c 100644
--- a/src/Spec2-Adapters-Morphic/SpMorphicBackend.class.st
+++ b/src/Spec2-Adapters-Morphic/SpMorphicBackend.class.st
@@ -62,7 +62,7 @@ SpMorphicBackend >> inform: aString [
 	"If we are not in interactive mode, we log in the stdout. Else we delegate to the Morphic notification"
 
 	Smalltalk isInteractive
-		ifTrue: [ GrowlMorph openWithLabel: 'Information' translated contents: aString ]
+		ifTrue: [ GrowlMorph openWithLabel: 'Information' contents: aString ]
 		ifFalse: [
 				| logBlock |
 				logBlock := [ :logger |
@@ -99,7 +99,7 @@ SpMorphicBackend >> notifyError: aSpecNotification [
 SpMorphicBackend >> notifyInfo: aSpecNotification [
 
 	GrowlMorph 
-		openWithLabel: 'Information' translated 
+		openWithLabel: 'Information' 
 		contents: aSpecNotification message
 ]
 
diff --git a/src/Spec2-Adapters-Morphic/SpMorphicPanedLayout.class.st b/src/Spec2-Adapters-Morphic/SpMorphicPanedLayout.class.st
index 70be4c3f..22ed9f4e 100644
--- a/src/Spec2-Adapters-Morphic/SpMorphicPanedLayout.class.st
+++ b/src/Spec2-Adapters-Morphic/SpMorphicPanedLayout.class.st
@@ -1,22 +1,21 @@
 "
-I'm a table layout for PanedLayouts. 
-I add some posibilities to layouting (like defining the initial position in proportional 
-numbers instead a fixed number).
-
-This is needed because sometimes I want to express a position like: 
-
-SpecPanedLayout new 
-	position: 80 percent;
-	...
-	
-instead a fixed number I may change in other places.
- 
+I am a specialized TableLayout for PanedLayouts in the Morphic adapter.
+
+I manage rigid and spaceFill resizing constraints for the first and second child submorphs based on `#position`:
+- Fixed values (|position| >= 1):
+    Positive (e.g. 200): First submorph is rigid with specified width/height; last submorph is spaceFill.
+    Negative (e.g. -200): Last submorph is rigid with absolute width/height; first submorph is spaceFill.
+- Proportional values (|position| < 1):
+    Submorph sizes are updated proportionally on layout passes.
+- Splitter interaction:
+    When the splitter is dragged, the sizing mode (fixed vs proportional, start vs end) is preserved rather than being forcibly coerced into a percentage.
 "
 Class {
 	#name : 'SpMorphicPanedLayout',
 	#superclass : 'TableLayout',
 	#instVars : [
-		'position'
+		'position',
+		'isResizing'
 	],
 	#category : 'Spec2-Adapters-Morphic-Layout',
 	#package : 'Spec2-Adapters-Morphic',
@@ -24,40 +23,87 @@ Class {
 }
 
 { #category : 'private' }
-SpMorphicPanedLayout >> ensureHeightPosition: aMorph in: aRect [
-	| firstMorph height |
+SpMorphicPanedLayout >> computePreservedPositionOn: layoutedMorph [
+	| targetMorph newDimension delta |
+	targetMorph := self isFromEnd
+		ifTrue: [ layoutedMorph submorphs last ]
+		ifFalse: [ layoutedMorph submorphs first ].
+
+	newDimension := self isHorizontal
+		ifTrue: [ targetMorph width ]
+		ifFalse: [ targetMorph height ].
+
+	self isFixed ifTrue: [
+		^ self isFromEnd
+			ifTrue: [ newDimension asInteger negated ]
+			ifFalse: [ newDimension asInteger ] ].
+
+	delta := self isHorizontal
+		ifTrue: [ (newDimension * 100 / layoutedMorph width) asInteger percent ]
+		ifFalse: [ (newDimension * 100 / layoutedMorph height) asInteger percent ].
+
+	^ self isFromEnd
+		ifTrue: [ delta negated ]
+		ifFalse: [ delta ]
+]
 
+{ #category : 'private' }
+SpMorphicPanedLayout >> ensureHeightPosition: aMorph in: aRect [
+	| targetMorph otherMorph height |
 	self position ifNil: [ ^ self ].
+	self isResizing ifTrue: [ ^ self ].
+	aMorph submorphs size < 3 ifTrue: [ ^ self ].
+
+	targetMorph := self isFromEnd
+		ifTrue: [ aMorph submorphs last ]
+		ifFalse: [ aMorph submorphs first ].
+	otherMorph := self isFromEnd
+		ifTrue: [ aMorph submorphs first ]
+		ifFalse: [ aMorph submorphs last ].
+
+	targetMorph vResizing = #rigid ifFalse: [ targetMorph vResizing: #rigid ].
+	otherMorph vResizing = #spaceFill ifFalse: [ otherMorph vResizing: #spaceFill ].
 
-	firstMorph := aMorph submorphs first.
-	firstMorph vResizing = #rigid 
-		ifFalse: [ firstMorph vResizing: #rigid ].
 	height := self heightPositionIn: aRect extent.
-	firstMorph height = height
-		ifFalse: [ firstMorph height: height ]
+	targetMorph height = height ifFalse: [ targetMorph height: height ]
 ]
 
 { #category : 'private' }
 SpMorphicPanedLayout >> ensureWidthPosition: aMorph in: aRect [
-	| firstMorph width |
-
+	| targetMorph otherMorph width |
 	self position ifNil: [ ^ self ].
+	self isResizing ifTrue: [ ^ self ].
+	aMorph submorphs size < 3 ifTrue: [ ^ self ].
+
+	targetMorph := self isFromEnd
+		ifTrue: [ aMorph submorphs last ]
+		ifFalse: [ aMorph submorphs first ].
+	otherMorph := self isFromEnd
+		ifTrue: [ aMorph submorphs first ]
+		ifFalse: [ aMorph submorphs last ].
+
+	targetMorph hResizing = #rigid ifFalse: [ targetMorph hResizing: #rigid ].
+	otherMorph hResizing = #spaceFill ifFalse: [ otherMorph hResizing: #spaceFill ].
 
-	firstMorph := aMorph submorphs first.
-	firstMorph hResizing = #rigid 
-		ifFalse: [ firstMorph hResizing: #rigid ].
 	width := self widthPositionIn: aRect extent.
-	firstMorph width = width 
-		ifFalse: [ firstMorph width: width ].
-	 
+	targetMorph width = width ifFalse: [ targetMorph width: width ]
 ]
 
 { #category : 'private' }
-SpMorphicPanedLayout >> heightPositionIn: aPoint [ 
+SpMorphicPanedLayout >> heightPositionIn: aPoint [
+	self position ifNil: [ ^ (aPoint y * 0.5) asInteger ].
+	self isFixed ifTrue: [ ^ self position abs asInteger ].
+	^ (aPoint y * self position abs) asInteger
+]
 
-	^ self position < 1 
-		ifTrue: [ (aPoint y * self position) asInteger ]
-		ifFalse: [ self position ]
+{ #category : 'testing' }
+SpMorphicPanedLayout >> isFixed [
+	^ self position isNotNil and: [ self position abs >= 1 ]
+]
+
+{ #category : 'testing' }
+SpMorphicPanedLayout >> isFromEnd [
+	^ self position isNotNil and: [ self position < 0 ]
 ]
 
 { #category : 'testing' }
@@ -67,14 +113,19 @@ SpMorphicPanedLayout >> isHorizontal [
 		or: [ properties listDirection == #bottomToTop ]) not
 ]
 
-{ #category : 'private' }
+{ #category : 'testing' }
+SpMorphicPanedLayout >> isResizing [
+	^ isResizing ifNil: [ false ]
+]
+
+{ #category : 'layout' }
 SpMorphicPanedLayout >> layoutLeftToRight: aMorph in: newBounds [
 
 	self ensureWidthPosition: aMorph in: newBounds.
 	super layoutLeftToRight: aMorph in: newBounds
 ]
 
-{ #category : 'private' }
+{ #category : 'layout' }
 SpMorphicPanedLayout >> layoutTopToBottom: aMorph in: newBounds [
 
 	self ensureHeightPosition: aMorph in: newBounds.
@@ -88,29 +139,28 @@ SpMorphicPanedLayout >> position [
 
 { #category : 'accessing' }
 SpMorphicPanedLayout >> position: anObject [
-	position := anObject
+	position := anObject.
+	isResizing := false
 ]
 
-{ #category : 'accessing' }
+{ #category : 'actions' }
 SpMorphicPanedLayout >> preservePositionProportionOn: layoutedMorph [
+	isResizing := false.
+	layoutedMorph submorphs size < 3 ifTrue: [ ^ self ].
 
-	| referenceMorph |
-	referenceMorph := layoutedMorph submorphs first.
-	position := self isHorizontal
-		            ifTrue: [ (referenceMorph width * 100 / layoutedMorph width) asInteger percent ]
-		            ifFalse: [ (referenceMorph height * 100 / layoutedMorph height) asInteger percent ]
+	position := self computePreservedPositionOn: layoutedMorph.
+	layoutedMorph layoutChanged
 ]
 
-{ #category : 'accessing' }
+{ #category : 'actions' }
 SpMorphicPanedLayout >> resetPosition [
-
-	position := nil
+	"Flag that splitter dragging is active so intermediate relayout passes do not override manual adjustment."
+	isResizing := true
 ]
 
 { #category : 'private' }
 SpMorphicPanedLayout >> widthPositionIn: aPoint [
-
-	^ self position < 1
-		  ifTrue: [ (aPoint x * self position) asInteger ]
-		  ifFalse: [ self position ]
+	self position ifNil: [ ^ (aPoint x * 0.5) asInteger ].
+	self isFixed ifTrue: [ ^ self position abs asInteger ].
+	^ (aPoint x * self position abs) asInteger
 ]
diff --git a/src/Spec2-Adapters-Morphic/SpNotebookMorph.class.st b/src/Spec2-Adapters-Morphic/SpNotebookMorph.class.st
index ae4a8b52..e6a3bbd6 100644
--- a/src/Spec2-Adapters-Morphic/SpNotebookMorph.class.st
+++ b/src/Spec2-Adapters-Morphic/SpNotebookMorph.class.st
@@ -104,7 +104,7 @@ SpNotebookMorph >> newCloseButtonFor: aSpNotebookPage [
 		newCloseControlIn: self
 		for: aSpNotebookPage
 		action: [ aSpNotebookPage removeFromNotebook ]
-		help: 'Close this page' translated
+		help: 'Close this page'
 ]
 
 { #category : 'factory' }
diff --git a/src/Spec2-Adapters-Morphic/SpPanedResizerHorizontalMorph.class.st b/src/Spec2-Adapters-Morphic/SpPanedResizerHorizontalMorph.class.st
index 343cff4e..5198a48b 100644
--- a/src/Spec2-Adapters-Morphic/SpPanedResizerHorizontalMorph.class.st
+++ b/src/Spec2-Adapters-Morphic/SpPanedResizerHorizontalMorph.class.st
@@ -44,16 +44,21 @@ SpPanedResizerHorizontalMorph >> setLayoutSizing [
 
 { #category : 'private' }
 SpPanedResizerHorizontalMorph >> setTargetBounds [
-	| target |
-	
-	target := self target.
-	target bounds: (target bounds withRight: self left - 1)
+	self target ifNotNil: [ :t |
+		t bounds: (t bounds withRight: self left) ].
+	self targetAfter ifNotNil: [ :ta |
+		ta bounds: (self right @ ta top corner: ta bottomRight) ]
 ]
 
 { #category : 'private' }
 SpPanedResizerHorizontalMorph >> setTargetLayoutSizing [
-
-	(self target hResizing = #rigid) ifTrue: [ ^ self ].
-	self target hResizing: #rigid.
-	self targetAfter hResizing: #spaceFill.
+	self isFromEnd
+		ifTrue: [
+			self targetAfter hResizing = #rigid ifTrue: [ ^ self ].
+			self targetAfter hResizing: #rigid.
+			self target hResizing: #spaceFill ]
+		ifFalse: [
+			self target hResizing = #rigid ifTrue: [ ^ self ].
+			self target hResizing: #rigid.
+			self targetAfter hResizing: #spaceFill ]
 ]
diff --git a/src/Spec2-Adapters-Morphic/SpPanedResizerMorph.class.st b/src/Spec2-Adapters-Morphic/SpPanedResizerMorph.class.st
index 8b2e8688..764570b6 100644
--- a/src/Spec2-Adapters-Morphic/SpPanedResizerMorph.class.st
+++ b/src/Spec2-Adapters-Morphic/SpPanedResizerMorph.class.st
@@ -129,6 +129,13 @@ SpPanedResizerMorph >> initialize [
 		extent: self defaultWidth @ self defaultHeight
 ]
 
+{ #category : 'testing' }
+SpPanedResizerMorph >> isFromEnd [
+	^ self owner
+		ifNotNil: [ :o | o layoutPolicy ifNotNil: [ :lp | lp isFromEnd ] ]
+		ifNil: [ false ]
+]
+
 { #category : 'testing' }
 SpPanedResizerMorph >> isHorizontal [
 	"Answer true if the receiver has a horizontal layout."
diff --git a/src/Spec2-Adapters-Morphic/SpPanedResizerVerticalMorph.class.st b/src/Spec2-Adapters-Morphic/SpPanedResizerVerticalMorph.class.st
index 8e40c7e0..e1377853 100644
--- a/src/Spec2-Adapters-Morphic/SpPanedResizerVerticalMorph.class.st
+++ b/src/Spec2-Adapters-Morphic/SpPanedResizerVerticalMorph.class.st
@@ -43,16 +43,21 @@ SpPanedResizerVerticalMorph >> setLayoutSizing [
 
 { #category : 'private' }
 SpPanedResizerVerticalMorph >> setTargetBounds [
-
-	| target |
-	target := self target.
-	target bounds: (target position corner: (target right @ (self top - 1)))
+	self target ifNotNil: [ :t |
+		t bounds: (t position corner: (t right @ self top)) ].
+	self targetAfter ifNotNil: [ :ta |
+		ta bounds: (ta left @ self bottom corner: ta bottomRight) ]
 ]
 
 { #category : 'private' }
 SpPanedResizerVerticalMorph >> setTargetLayoutSizing [
-
-	(self target vResizing = #rigid) ifTrue: [ ^ self ].
-	self target vResizing: #rigid.
-	self targetAfter vResizing: #spaceFill
+	self isFromEnd
+		ifTrue: [
+			self targetAfter vResizing = #rigid ifTrue: [ ^ self ].
+			self targetAfter vResizing: #rigid.
+			self target vResizing: #spaceFill ]
+		ifFalse: [
+			self target vResizing = #rigid ifTrue: [ ^ self ].
+			self target vResizing: #rigid.
+			self targetAfter vResizing: #spaceFill ]
 ]
diff --git a/src/Spec2-Backend-Tests/SpAbstractListAdapterSingleSelectionTest.class.st b/src/Spec2-Backend-Tests/SpAbstractListAdapterSingleSelectionTest.class.st
index 5fdc6179..1617344f 100644
--- a/src/Spec2-Backend-Tests/SpAbstractListAdapterSingleSelectionTest.class.st
+++ b/src/Spec2-Backend-Tests/SpAbstractListAdapterSingleSelectionTest.class.st
@@ -182,5 +182,6 @@ SpAbstractListAdapterSingleSelectionTest >> testUnselectWidgetIndexRaisesSelecti
 	presenter selection
 		whenChangedDo: [ :selection | selectedIndex := selection selectedIndex ].
 	self adapter selectIndex: 0.
+	backendForTest waitUntilUIRedrawed.
 	self assert: selectedIndex equals: 0
 ]
diff --git a/src/Spec2-Backend-Tests/SpPanedLayoutAdapterTest.class.st b/src/Spec2-Backend-Tests/SpPanedLayoutAdapterTest.class.st
index 8d323707..75d83a74 100644
--- a/src/Spec2-Backend-Tests/SpPanedLayoutAdapterTest.class.st
+++ b/src/Spec2-Backend-Tests/SpPanedLayoutAdapterTest.class.st
@@ -80,6 +80,21 @@ SpPanedLayoutAdapterTest >> testAddSecondTwiceSetsChildrenSingleTime [
 	self assert: self adapter children size equals: 1
 ]
 
+{ #category : 'tests' }
+SpPanedLayoutAdapterTest >> testBuildWithVariousSliderPositions [
+	layout positionOfSlider: -200.
+	layout first: SpButtonPresenter new.
+	layout second: SpButtonPresenter new.
+	self openInstance.
+	self assert: self adapter children size equals: 2.
+
+	layout positionOfSlider: 300.
+	self assert: layout positionOfSlider equals: 300.
+
+	layout positionOfSlider: -0.3.
+	self assert: layout positionOfSlider closeTo: -0.3
+]
+
 { #category : 'tests' }
 SpPanedLayoutAdapterTest >> testLayoutWithFirstElementIsNotEmpty [
 
diff --git a/src/Spec2-Backend-Tests/SpTreeAdapterSingleSelectionTest.class.st b/src/Spec2-Backend-Tests/SpTreeAdapterSingleSelectionTest.class.st
index 6d848c83..fba08f57 100644
--- a/src/Spec2-Backend-Tests/SpTreeAdapterSingleSelectionTest.class.st
+++ b/src/Spec2-Backend-Tests/SpTreeAdapterSingleSelectionTest.class.st
@@ -172,5 +172,6 @@ SpTreeAdapterSingleSelectionTest >> testUnselectWidgetIndexRaisesSelectionIndexC
 	presenter selection 
 		whenChangedDo: [ :selection | selectedPath := selection ].
 	self adapter selectPath: #().
+	backendForTest waitUntilUIRedrawed.
 	self assertEmpty: selectedPath
 ]
diff --git a/src/Spec2-Backend-Tests/SpTreeTableAdapterSingleSelectionTest.class.st b/src/Spec2-Backend-Tests/SpTreeTableAdapterSingleSelectionTest.class.st
index 35147888..843799ee 100644
--- a/src/Spec2-Backend-Tests/SpTreeTableAdapterSingleSelectionTest.class.st
+++ b/src/Spec2-Backend-Tests/SpTreeTableAdapterSingleSelectionTest.class.st
@@ -191,5 +191,6 @@ SpTreeTableAdapterSingleSelectionTest >> testUnselectWidgetIndexRaisesSelectionI
 	presenter selection 
 		whenChangedDo: [ :selection | selectedPath := selection ].
 	self adapter selectPath: #().
+	backendForTest waitUntilUIRedrawed.
 	self assertEmpty: selectedPath
 ]
diff --git a/src/Spec2-Code/SpCodePresenter.class.st b/src/Spec2-Code/SpCodePresenter.class.st
index 06eb8517..12dc44d1 100644
--- a/src/Spec2-Code/SpCodePresenter.class.st
+++ b/src/Spec2-Code/SpCodePresenter.class.st
@@ -331,11 +331,12 @@ SpCodePresenter >> doBrowseSenders [
 
 	| variableOrClassName variable |
 	variableOrClassName := self selectedSelector ifNil: [ ^ nil ].
-	variable := self lookupEnvironment lookupVar: variableOrClassName. "For global and class variables, sender-of shows intead the using methods"
+	variable := self lookupEnvironment lookupVar: variableOrClassName.
+	
+	"For global and class variables, sender-of shows intead the using methods"
 	(variable isNotNil and: [ variable isGlobalVariable or: [ variable isClassVariable ] ])
 		ifTrue: [ self systemNavigation openBrowserFor: variable withMethods: variable usingMethods ]
-		ifFalse: [
-		(Smalltalk tools toolNamed: #messageList) browseSendersOfAll: { variableOrClassName } from: self interactionModel behavior ]
+		ifFalse: [ self systemNavigation browseAllSendersOf: variableOrClassName ]
 ]
 
 { #category : 'private - bindings' }
diff --git a/src/Spec2-Examples/SpPanedLayout.extension.st b/src/Spec2-Examples/SpPanedLayout.extension.st
index 83d93978..b909b759 100644
--- a/src/Spec2-Examples/SpPanedLayout.extension.st
+++ b/src/Spec2-Examples/SpPanedLayout.extension.st
@@ -1,5 +1,41 @@
 Extension { #name : 'SpPanedLayout' }
 
+{ #category : '*Spec2-Examples' }
+SpPanedLayout class >> exampleFixedFromEnd [
+	<example>
+	| presenter text form |
+	presenter := SpPresenter new.
+	presenter layout: (SpPanedLayout newLeftToRight
+		positionOfSlider: -260;
+		add: (text := presenter newText);
+		add: (form := presenter newList);
+		yourself).
+
+	text text: 'Fixed end layout (-260 px).
+The right properties panel keeps its fixed width (260 px) when the window is resized.
+Dragging the splitter updates the fixed width from the right edge.'.
+	form items: #( 'Property 1: True' 'Property 2: #auto' 'Property 3: 42' ).
+	presenter openWithTitle: 'SpPanedLayout - Fixed Right (-260 px)'
+]
+
+{ #category : '*Spec2-Examples' }
+SpPanedLayout class >> exampleFixedFromStart [
+	<example>
+	| presenter list text |
+	presenter := SpPresenter new.
+	presenter layout: (SpPanedLayout newLeftToRight
+		positionOfSlider: 220;
+		add: (list := presenter newList);
+		add: (text := presenter newText);
+		yourself).
+
+	list items: #( 'Project Tree' 'Packages' 'Classes' 'Methods' ).
+	text text: 'Fixed start layout (220 px).
+The left list keeps its fixed width when the window is resized.
+Dragging the splitter updates the fixed pixel width.'.
+	presenter openWithTitle: 'SpPanedLayout - Fixed Left (220 px)'
+]
+
 { #category : '*Spec2-Examples' }
 SpPanedLayout class >> exampleNotResizingStartChild [ 
 	<example>
@@ -19,3 +55,21 @@ SpPanedLayout class >> exampleNotResizingStartChild [
 
 	presenter open
 ]
+
+{ #category : '*Spec2-Examples' }
+SpPanedLayout class >> exampleProportional [
+	<example>
+	| presenter list text |
+	presenter := SpPresenter new.
+	presenter layout: (SpPanedLayout newLeftToRight
+		positionOfSlider: 30 percent;
+		add: (list := presenter newList);
+		add: (text := presenter newText);
+		yourself).
+
+	list items: (1 to: 50).
+	text text: 'Proportional layout (30% / 70%).
+Both panels resize proportionally when the window is resized.
+Dragging the splitter keeps proportional behavior.'.
+	presenter openWithTitle: 'SpPanedLayout - Proportional (30%)'
+]
diff --git a/src/Spec2-Examples/SpPanedLayoutExamplePage.class.st b/src/Spec2-Examples/SpPanedLayoutExamplePage.class.st
new file mode 100644
index 00000000..4065966f
--- /dev/null
+++ b/src/Spec2-Examples/SpPanedLayoutExamplePage.class.st
@@ -0,0 +1,25 @@
+"
+I am the demo page descriptor for SpPanedLayoutExamplePresenter in the Spec2 demo browser.
+"
+Class {
+	#name : 'SpPanedLayoutExamplePage',
+	#superclass : 'SpDemoPage',
+	#category : 'Spec2-Examples-Demo-Layouts',
+	#package : 'Spec2-Examples',
+	#tag : 'Demo-Layouts'
+}
+
+{ #category : 'initialization' }
+SpPanedLayoutExamplePage class >> pageName [
+	^ 'Paned Layouts'
+]
+
+{ #category : 'initialization' }
+SpPanedLayoutExamplePage class >> priority [
+	^ 2150
+]
+
+{ #category : 'initialization' }
+SpPanedLayoutExamplePage >> pageClass [
+	^ SpPanedLayoutExamplePresenter
+]
diff --git a/src/Spec2-Examples/SpPanedLayoutExamplePresenter.class.st b/src/Spec2-Examples/SpPanedLayoutExamplePresenter.class.st
new file mode 100644
index 00000000..335443b4
--- /dev/null
+++ b/src/Spec2-Examples/SpPanedLayoutExamplePresenter.class.st
@@ -0,0 +1,71 @@
+"
+I am an interactive demo presenter showcasing SpPanedLayout capabilities.
+
+I provide controls to switch between fixed-start (+200 px), fixed-end (-200 px), and proportional (30%, -30%) modes, demonstrating window resizing and splitter dragging behavior.
+"
+Class {
+	#name : 'SpPanedLayoutExamplePresenter',
+	#superclass : 'SpPresenter',
+	#instVars : [
+		'textPresenter',
+		'listPresenter',
+		'modeLabel',
+		'btnPropStart',
+		'btnPropEnd',
+		'btnFixStart',
+		'btnFixEnd'
+	],
+	#category : 'Spec2-Examples-Demo-Layouts',
+	#package : 'Spec2-Examples',
+	#tag : 'Demo-Layouts'
+}
+
+{ #category : 'actions' }
+SpPanedLayoutExamplePresenter >> applyLayout: aPosition label: aDescription [
+	modeLabel label: 'Current mode: ', aDescription.
+	self layout: (SpBoxLayout newTopToBottom
+		add: (SpBoxLayout newLeftToRight
+			add: btnFixStart;
+			add: btnFixEnd;
+			add: btnPropStart;
+			add: btnPropEnd;
+			yourself) expand: false;
+		add: modeLabel expand: false;
+		add: (SpPanedLayout newLeftToRight
+			positionOfSlider: aPosition;
+			add: listPresenter;
+			add: textPresenter;
+			yourself);
+		yourself)
+]
+
+{ #category : 'layout' }
+SpPanedLayoutExamplePresenter >> defaultLayout [
+	^ SpBoxLayout newTopToBottom
+]
+
+{ #category : 'initialization' }
+SpPanedLayoutExamplePresenter >> initializePresenters [
+	textPresenter := self newText
+		text: 'Resize this window or drag the splitter to observe panel resizing.';
+		yourself.
+	listPresenter := self newList
+		items: (1 to: 100);
+		yourself.
+	modeLabel := self newLabel.
+
+	btnPropStart := self newButton
+		label: '30% Start';
+		action: [ self applyLayout: 30 percent label: 'Proportional 30% from start (0.3)' ].
+	btnPropEnd := self newButton
+		label: '30% End';
+		action: [ self applyLayout: -30 percent label: 'Proportional 30% from end (-0.3)' ].
+	btnFixStart := self newButton
+		label: '200px Start';
+		action: [ self applyLayout: 200 label: 'Fixed 200px from start (+200)' ].
+	btnFixEnd := self newButton
+		label: '200px End';
+		action: [ self applyLayout: -200 label: 'Fixed 200px from end (-200)' ].
+
+	self applyLayout: 200 label: 'Fixed 200px from start (+200)'.
+]
diff --git a/src/Spec2-Layout/SpPanedLayout.class.st b/src/Spec2-Layout/SpPanedLayout.class.st
index 74c375b7..fe0a2164 100644
--- a/src/Spec2-Layout/SpPanedLayout.class.st
+++ b/src/Spec2-Layout/SpPanedLayout.class.st
@@ -1,8 +1,13 @@
 "
-A layout with two **adjustable** panels. 
-A paned layout manages two and only two children, a first and a second one.
+A layout with two adjustable panels separated by a draggable splitter.
 
-From that perspective, a paned layout is like a `SpBoxLayout`: it places childen in vertical or horizontal fashion, but it will add a splitter in between, that user can drag to resize the panel.
+A paned layout manages exactly two children (first and second).
+The position and sizing behavior of the panes is controlled by `#positionOfSlider:`:
+
+- Values with absolute magnitude < 1 (e.g. 0.3, 30 percent, -0.2) define proportional splits that resize dynamically when the container is resized.
+- Values with absolute magnitude >= 1 (e.g. 200, -200) define fixed pixel sizes that do not resize with the window.
+- Positive values anchor the fixed/proportional constraint to the start pane (left or top).
+- Negative values anchor the fixed/proportional constraint to the end pane (right or bottom).
 "
 Class {
 	#name : 'SpPanedLayout',
@@ -145,13 +150,21 @@ SpPanedLayout >> positionOfSlider [
 
 { #category : 'api' }
 SpPanedLayout >> positionOfSlider: aNumber [
-	"Position of the slider. 
-	 - `aNumber` can be a fixed number indicating the exact position where the slider will 
-	 be placed in the pane.
-	 - `aFloat` can also be a fraction or a percentage, indicating the percentage position 
-	 of the slider, e.g. 30 percent (0.3) indicates the slider will be place at 1/3 of the panel."
+	"Sets the position and sizing mode of the paned splitter:
+
+	- Proportional sizing (|aNumber| < 1):
+	    Positive (e.g. 0.3 or 30 percent): Splitted proportionally from the start (left or top).
+	    Negative (e.g. -0.3 or -30 percent): Splitted proportionally from the end (right or bottom).
+	    Both panes resize proportionally when the container is resized.
+
+	- Fixed sizing (|aNumber| >= 1):
+	    Positive integer (e.g. 200): Fixed offset in pixels from the start (left or top).
+	      The start pane retains its fixed width/height when the window is resized.
+	    Negative integer (e.g. -200): Fixed offset in pixels from the end (right or bottom).
+	      The end pane retains its fixed width/height when the window is resized.
 
-  positionOfSlider := aNumber
+	When the user drags the splitter, the sizing mode (fixed vs proportional, start vs end) is preserved."
+	positionOfSlider := aNumber
 ]
 
 { #category : 'api' }
diff --git a/src/Spec2-Morphic-Backend-Tests/SpMorphicPanedLayoutTest.class.st b/src/Spec2-Morphic-Backend-Tests/SpMorphicPanedLayoutTest.class.st
index 35db91fd..43abba71 100644
--- a/src/Spec2-Morphic-Backend-Tests/SpMorphicPanedLayoutTest.class.st
+++ b/src/Spec2-Morphic-Backend-Tests/SpMorphicPanedLayoutTest.class.st
@@ -17,6 +17,55 @@ SpMorphicPanedLayoutTest >> tearDown [
 	super tearDown
 ]
 
+{ #category : 'tests' }
+SpMorphicPanedLayoutTest >> testFixedPositionFromBottom [
+	| panel m1 m2 layout |
+	layout := SpMorphicPanedLayout new.
+	layout position: -150.
+	panel := PanelMorph new
+		layoutPolicy: layout;
+		listDirection: #topToBottom;
+		bounds: (0@0 extent: 600@800);
+		addMorphBack: (m1 := Morph new extent: 100@100; hResizing: #spaceFill; vResizing: #spaceFill; yourself);
+		addMorphBack: SpPanedResizerMorph newVertical;
+		addMorphBack: (m2 := Morph new extent: 100@100; hResizing: #spaceFill; vResizing: #spaceFill; yourself);
+		yourself.
+	panel fullBounds.
+
+	self assert: m2 height equals: 150.
+	self assert: m2 vResizing equals: #rigid.
+	self assert: m1 vResizing equals: #spaceFill.
+
+	panel extent: 600@1000.
+	panel fullBounds.
+	self assert: m2 height equals: 150.
+]
+
+{ #category : 'tests' }
+SpMorphicPanedLayoutTest >> testFixedPositionFromRight [
+	| panel m1 m2 layout |
+	layout := SpMorphicPanedLayout new.
+	layout position: -200.
+	panel := PanelMorph new
+		layoutPolicy: layout;
+		listDirection: #leftToRight;
+		bounds: (0@0 extent: 800@600);
+		addMorphBack: (m1 := Morph new extent: 100@100; hResizing: #spaceFill; vResizing: #spaceFill; yourself);
+		addMorphBack: SpPanedResizerMorph newHorizontal;
+		addMorphBack: (m2 := Morph new extent: 100@100; hResizing: #spaceFill; vResizing: #spaceFill; yourself);
+		yourself.
+	panel fullBounds.
+
+	self assert: m2 width equals: 200.
+	self assert: m2 hResizing equals: #rigid.
+	self assert: m1 hResizing equals: #spaceFill.
+
+	"Resizing window: the right panel must retain its 200 px fixed width"
+	panel extent: 1000@600.
+	panel fullBounds.
+	self assert: m2 width equals: 200
+]
+
 { #category : 'tests' }
 SpMorphicPanedLayoutTest >> testListTakesAssignedSpace [
 
@@ -38,6 +87,33 @@ SpMorphicPanedLayoutTest >> testListTakesAssignedSpace [
 		equals: list adapter widget width
 ]
 
+{ #category : 'tests' }
+SpMorphicPanedLayoutTest >> testPresenterWithFixedPositionFromRight [
+	| presenter leftBtn rightBtn |
+	presenter := SpPresenter new.
+	presenter application: SpApplication new.
+	presenter layout: (SpPanedLayout newLeftToRight
+		positionOfSlider: -200;
+		first: (leftBtn := presenter newButton label: 'Left');
+		second: (rightBtn := presenter newButton label: 'Right');
+		yourself).
+
+	[ 
+		presenter open.
+		presenter window extent: 800@600.
+		presenter window adapter widget fullBounds.
+		
+		self assert: rightBtn adapter widget width equals: 200.
+		self assert: rightBtn adapter widget hResizing equals: #rigid.
+		self assert: leftBtn adapter widget hResizing equals: #spaceFill.
+		
+		"Resizing window: the right button must retain its 200 px fixed width"
+		presenter window extent: 1000@600.
+		presenter window adapter widget fullBounds.
+		self assert: rightBtn adapter widget width equals: 200.
+	] ensure: [ presenter window close ]
+]
+
 { #category : 'tests' }
 SpMorphicPanedLayoutTest >> testReplacePresenter [
 
@@ -60,3 +136,110 @@ SpMorphicPanedLayoutTest >> testReplacePresenter [
 	self assert: widget submorphs size equals: 3. "one plus for the slider"
 	self assert: widget submorphs first equals: p3 adapter widget
 ]
+
+{ #category : 'tests' }
+SpMorphicPanedLayoutTest >> testSplitterDragPreservesFixedPositionFromLeft [
+	| panel resizer m1 m2 layout dragDelta startCenter endCenter |
+	layout := SpMorphicPanedLayout new.
+	layout position: 200.
+	panel := PanelMorph new
+		layoutPolicy: layout;
+		listDirection: #leftToRight;
+		bounds: (0@0 extent: 800@600);
+		addMorphBack: (m1 := Morph new extent: 100@100; hResizing: #spaceFill; vResizing: #spaceFill; yourself);
+		addMorphBack: (resizer := SpPanedResizerMorph newHorizontal);
+		addMorphBack: (m2 := Morph new extent: 100@100; hResizing: #spaceFill; vResizing: #spaceFill; yourself);
+		yourself.
+	panel fullBounds.
+
+	dragDelta := 50.
+	startCenter := resizer center.
+	endCenter := (startCenter x + dragDelta) @ startCenter y.
+
+	resizer mouseDown: (MouseButtonEvent new
+		setType: #mouseDown
+		position: startCenter
+		which: MouseButtonEvent redButton
+		buttons: MouseButtonEvent redButton
+		hand: HandMorph new
+		stamp: Time millisecondClockValue).
+
+	resizer mouseMove: (MouseMoveEvent new
+		setType: #mouseMove
+		startPoint: startCenter
+		endPoint: endCenter
+		trail: { startCenter. endCenter }
+		buttons: MouseButtonEvent redButton
+		hand: HandMorph new
+		stamp: Time millisecondClockValue).
+
+	resizer mouseUp: (MouseButtonEvent new
+		setType: #mouseUp
+		position: endCenter
+		which: MouseButtonEvent redButton
+		buttons: 0
+		hand: HandMorph new
+		stamp: Time millisecondClockValue).
+
+	self assert: layout position isInteger.
+	self assert: layout position equals: 250.
+	self assert: m1 width equals: 250.
+
+	"Resizing window: panel must retain 250 px and not convert to percentage"
+	panel extent: 1000@600.
+	panel fullBounds.
+	self assert: m1 width equals: 250
+]
+
+{ #category : 'tests' }
+SpMorphicPanedLayoutTest >> testSplitterDragPreservesFixedPositionFromRight [
+	| panel resizer m1 m2 layout dragDelta startCenter endCenter |
+	layout := SpMorphicPanedLayout new.
+	layout position: -200.
+	panel := PanelMorph new
+		layoutPolicy: layout;
+		listDirection: #leftToRight;
+		bounds: (0@0 extent: 800@600);
+		addMorphBack: (m1 := Morph new extent: 100@100; hResizing: #spaceFill; vResizing: #spaceFill; yourself);
+		addMorphBack: (resizer := SpPanedResizerMorph newHorizontal);
+		addMorphBack: (m2 := Morph new extent: 100@100; hResizing: #spaceFill; vResizing: #spaceFill; yourself);
+		yourself.
+	panel fullBounds.
+
+	dragDelta := -50. "Dragging left expands the right morph m2"
+	startCenter := resizer center.
+	endCenter := (startCenter x + dragDelta) @ startCenter y.
+
+	resizer mouseDown: (MouseButtonEvent new
+		setType: #mouseDown
+		position: startCenter
+		which: MouseButtonEvent redButton
+		buttons: MouseButtonEvent redButton
+		hand: HandMorph new
+		stamp: Time millisecondClockValue).
+
+	resizer mouseMove: (MouseMoveEvent new
+		setType: #mouseMove
+		startPoint: startCenter
+		endPoint: endCenter
+		trail: { startCenter. endCenter }
+		buttons: MouseButtonEvent redButton
+		hand: HandMorph new
+		stamp: Time millisecondClockValue).
+
+	resizer mouseUp: (MouseButtonEvent new
+		setType: #mouseUp
+		position: endCenter
+		which: MouseButtonEvent redButton
+		buttons: 0
+		hand: HandMorph new
+		stamp: Time millisecondClockValue).
+
+	self assert: layout position isInteger.
+	self assert: layout position equals: -250.
+	self assert: m2 width equals: 250.
+
+	panel extent: 1000@600.
+	panel fullBounds.
+	self assert: m2 width equals: 250
+]
diff --git a/src/Spec2-Morphic-Tests/SpWorldPresenterTest.class.st b/src/Spec2-Morphic-Tests/SpWorldPresenterTest.class.st
index 73fe3740..f95926e9 100644
--- a/src/Spec2-Morphic-Tests/SpWorldPresenterTest.class.st
+++ b/src/Spec2-Morphic-Tests/SpWorldPresenterTest.class.st
@@ -33,44 +33,38 @@ SpWorldPresenterTest >> tearDown [
 
 { #category : 'tests' }
 SpWorldPresenterTest >> testOpenPresenterInWorldDisplayInFullWorld [
+
 	| buttonPresenter |
-	
-	buttonPresenter := (application newPresenter: SpButtonPresenter)
-		label: 'test'.
-	
+	buttonPresenter := (application instantiate: SpButtonPresenter) label: 'test'.
+
 	(SpTestWorldPresenter presenter: buttonPresenter) open.
-	
+
 	self currentWorld addMorph: worldMorph.
-	
-	self
-		assert: worldMorph submorphs first submorphs first extent
-		equals: worldMorph extent - 8 "border"
+
+	self assert: worldMorph submorphs first submorphs first extent equals: worldMorph extent - 8 "border"
 ]
 
 { #category : 'tests' }
 SpWorldPresenterTest >> testOpenPresenterInWorldDisplayToolbarDoesNotHidePresenter [
+
 	| windowPresenter worldPanel |
-	windowPresenter := application
-		newPresenter: SpTestPresenterWithToolbar.
-		
+	windowPresenter := application instantiate: SpTestPresenterWithToolbar.
+
 	(SpTestWorldPresenter presenter: windowPresenter) open.
-		
+
 	worldPanel := worldMorph submorphs first.
 	self
-		assert:
-			(worldPanel submorphs first bounds
-				intersect: worldPanel submorphs second bounds)
-				= (0 @ 0 extent: 0 @ 0)
+		assert: (worldPanel submorphs first bounds intersect: worldPanel submorphs second bounds) = (0 @ 0 extent: 0 @ 0)
 		description: 'toolbar should not intersect with presenter when opening in world'
 ]
 
 { #category : 'tests' }
 SpWorldPresenterTest >> testOpenPresenterInWorldRemoveExisitingMorphsInWorld [
+
 	| buttonPresenter |
 	worldMorph addMorph: CircleMorph new.
-	buttonPresenter := (application newPresenter: SpButtonPresenter)
-		label: 'testOpenPresenterInWorldRemoveExisitingMorphsInWorld'. 
-	
+	buttonPresenter := (application instantiate: SpButtonPresenter) label: 'testOpenPresenterInWorldRemoveExisitingMorphsInWorld'.
+
 	(SpTestWorldPresenter presenter: buttonPresenter) open.
 
 	self deny: (worldMorph submorphs anySatisfy: [ :morph | morph class = CircleMorph ]).
diff --git a/src/Spec2-Morphic/SpRGBSlidersPresenter.class.st b/src/Spec2-Morphic/SpRGBSlidersPresenter.class.st
index 7fecf863..03c3ac52 100644
--- a/src/Spec2-Morphic/SpRGBSlidersPresenter.class.st
+++ b/src/Spec2-Morphic/SpRGBSlidersPresenter.class.st
@@ -56,13 +56,13 @@ SpRGBSlidersPresenter >> initializePresenters [
 	blueSlider := self instantiate: SpSliderInputPresenter.
 	redSlider
 		min: 0;
-		max: 255; label: 'Red' translated.
+		max: 255; label: 'Red'.
 	greenSlider
 		min: 0;
-		max: 255; label: 'Green' translated.
+		max: 255; label: 'Green'.
 	blueSlider
 		min: 0;
-		max: 255; label: 'Blue' translated.
+		max: 255; label: 'Blue'.
 	self focusOrder
 		add: redSlider;
 		add: greenSlider;
diff --git a/src/Spec2-Tests/SpPanedLayoutTest.class.st b/src/Spec2-Tests/SpPanedLayoutTest.class.st
index f1cf1db1..15bbeeff 100644
--- a/src/Spec2-Tests/SpPanedLayoutTest.class.st
+++ b/src/Spec2-Tests/SpPanedLayoutTest.class.st
@@ -62,6 +62,15 @@ SpPanedLayoutTest >> testLayoutWithOneSecondElementIsNotEmpty [
 	self deny: layout isEmpty
 ]
 
+{ #category : 'tests' }
+SpPanedLayoutTest >> testPositionOfSliderAllowsNegativeValues [
+	layout positionOfSlider: -200.
+	self assert: layout positionOfSlider equals: -200.
+	
+	layout positionOfSlider: -30 percent.
+	self assert: layout positionOfSlider equals: -30 percent
+]
+
 { #category : 'running' }
 SpPanedLayoutTest >> testRemoveFirstElementFromLayoutTakesItOut [