diff --git a/packages/DomainCode-Core/Morph.extension.st b/packages/DomainCode-Core/Morph.extension.st
new file mode 100644
index 0000000..3aae4c4
--- /dev/null
+++ b/packages/DomainCode-Core/Morph.extension.st
@@ -0,0 +1,61 @@
+Extension { #name : #Morph }
+
+{ #category : #'*DomainCode-Core' }
+Morph >> allChildrenBreadthFirstDo: aBlock [
+
+	| remaining |
+	remaining := OrderedCollection with: self.
+	[remaining notEmpty] whileTrue: [ | next |
+		next := remaining removeFirst.
+		aBlock value: next.
+		remaining addAll: next children]
+]
+
+{ #category : #'*DomainCode-Core' }
+Morph >> allChildrenDo: aBlock [
+
+	self children do: [:c | c allChildrenDo: aBlock].
+	aBlock value: self
+]
+
+{ #category : #'*DomainCode-Core' }
+Morph >> allChildrenSelect: aBlock [
+
+	^ Array streamContents: [:stream | self allChildrenDo: [:b | (aBlock value: b) ifTrue: [stream nextPut: b]]]
+]
+
+{ #category : #'*DomainCode-Core' }
+Morph >> children [
+
+	^ submorphs
+]
+
+{ #category : #'*DomainCode-Core' }
+Morph >> firstDeepChildNode [
+
+	| current |
+	current := self.
+	[current children isEmpty] whileFalse: [current := current children first].
+	^ current
+]
+
+{ #category : #'*DomainCode-Core' }
+Morph >> hasChildren [
+
+	^ self children notEmpty
+]
+
+{ #category : #'*DomainCode-Core' }
+Morph >> isNode: aNode [
+
+	^ self = aNode
+]
+
+{ #category : #'*DomainCode-Core' }
+Morph >> treeSize [
+
+	| i |
+	i := 0.
+	self allChildrenDo: [:m | i := i + 1].
+	^ i
+]
diff --git a/packages/DomainCode-Diff/DCChawatheScriptGenerator.class.st b/packages/DomainCode-Diff/DCChawatheScriptGenerator.class.st
index abb6456..f8f5ca7 100644
--- a/packages/DomainCode-Diff/DCChawatheScriptGenerator.class.st
+++ b/packages/DomainCode-Diff/DCChawatheScriptGenerator.class.st
@@ -8,11 +8,11 @@ Class {
 DCChawatheScriptGenerator >> alignChildrenSrc: w dest: x srcInOrder: srcInOrder destInOrder: destInOrder in: aMapping [
 
 	| s1 s2 lcs |
-	w submorphs do: [:c | srcInOrder remove: c ifAbsent: []].
-	x submorphs do: [:c | destInOrder remove: c ifAbsent: []].
+	w children do: [:c | srcInOrder remove: c ifAbsent: []].
+	x children do: [:c | destInOrder remove: c ifAbsent: []].
 	
-	s1 := w submorphs select: [:c | (aMapping isSrcMapped: c) and: [x submorphs includes: (aMapping destForSrc: c)]].
-	s2 := x submorphs select: [:c | (aMapping isDestMapped: c) and: [w submorphs includes: (aMapping srcForDest: c)]].
+	s1 := w children select: [:c | (aMapping isSrcMapped: c) and: [x children includes: (aMapping destForSrc: c)]].
+	s2 := x children select: [:c | (aMapping isDestMapped: c) and: [w children includes: (aMapping srcForDest: c)]].
 	
 	lcs := self lcsWith: s1 and: s2 in: aMapping.
 	lcs do: [:mapping |
@@ -21,7 +21,7 @@ DCChawatheScriptGenerator >> alignChildrenSrc: w dest: x srcInOrder: srcInOrder
 	
 	s2 do: [:b |
 		s1 do: [:a |
-			((aMapping includes: {a. b}) and: [(lcs includes: {a. b}) not]) ifTrue: [ 
+			((aMapping includes: {a. b}) and: [(lcs includes: {a. b}) not]) ifTrue: [
 				self move: a to: w postDeleteDo: [self findPosition: b dest: destInOrder in: aMapping].
 				srcInOrder add: a.
 				destInOrder add: b]]]
@@ -37,7 +37,7 @@ DCChawatheScriptGenerator >> delete: aMorph [
 DCChawatheScriptGenerator >> findPosition: aTree dest: destInOrder in: aMapping [
 
 	| siblings v u |
-	siblings := aTree owner submorphs.
+	siblings := aTree owner children.
 	siblings do: [:c | (destInOrder includes: c) ifTrue: [c = aTree ifTrue: [^ 1]]].
 	
 	v := nil.
@@ -64,7 +64,7 @@ DCChawatheScriptGenerator >> generateFrom: src to: dest in: aMapping [
 	destInOrder := Set new.
 	inserted := Set new.
 	
-	dest allMorphsBreadthFirstDo: [:x | | y z w |
+	dest allChildrenBreadthFirstDo: [:x | | y z w |
 		w := nil.
 		y := x owner.
 		z := aMapping srcForDest: y.
@@ -81,13 +81,13 @@ DCChawatheScriptGenerator >> generateFrom: src to: dest in: aMapping [
 					v := w owner.
 					w treeLabel = x treeLabel ifFalse: [self update: w with: x contents].
 					k := self findPosition: x dest: destInOrder in: aMapping.
-					z = v ifFalse: [self move: w to: z postDeleteDo: [k]]]].
+					(z isNode: v) ifFalse: [self move: w to: z postDeleteDo: [k]]]].
 		
 		srcInOrder add: w.
 		destInOrder add: x.
 		self alignChildrenSrc: w dest: x srcInOrder: srcInOrder destInOrder: destInOrder in: aMapping].
 	
-	(Array streamContents: [:s | src allMorphsDo: [:w | ((aMapping isSrcMapped: w) not and: [(inserted includes: w) not]) ifTrue: [s nextPut: w]]]) do: [:w | self delete: w]
+	(Array streamContents: [:s | src allChildrenDo: [:w | ((aMapping isSrcMapped: w) not and: [(inserted includes: w) not]) ifTrue: [s nextPut: w]]]) do: [:w | self delete: w]
 ]
 
 { #category : #actions }
diff --git a/packages/DomainCode-Diff/DCCommandScriptGenerator.class.st b/packages/DomainCode-Diff/DCCommandScriptGenerator.class.st
index 1d370f9..2df779c 100644
--- a/packages/DomainCode-Diff/DCCommandScriptGenerator.class.st
+++ b/packages/DomainCode-Diff/DCCommandScriptGenerator.class.st
@@ -68,7 +68,7 @@ DCCommandScriptGenerator >> move: aMorph to: anOwnerMorph postDeleteDo: aBlock [
 	self editor do: command.
 	
 	self maybeAttachFlash: aMorph.
-	self logChanges ifTrue: [Transcript showln: {#move. anOwnerMorph. aBlock. aMorph}]
+	self logChanges ifTrue: [Transcript showln: {#move. anOwnerMorph. command index. aMorph}]
 ]
 
 { #category : #actions }
diff --git a/packages/DomainCode-Diff/DCGreedyBottomUpMatcher.class.st b/packages/DomainCode-Diff/DCGreedyBottomUpMatcher.class.st
index 4ac4a9d..c9f7e37 100644
--- a/packages/DomainCode-Diff/DCGreedyBottomUpMatcher.class.st
+++ b/packages/DomainCode-Diff/DCGreedyBottomUpMatcher.class.st
@@ -33,7 +33,7 @@ DCGreedyBottomUpMatcher >> destCandidatesFor: src in: aMapping [
 { #category : #'as yet unclassified' }
 DCGreedyBottomUpMatcher >> lastChanceMatchFrom: src to: dest in: aMapping [
 
-	(src recursiveSubmorphCount < self sizeThreshold or: [dest recursiveSubmorphCount < self sizeThreshold]) ifTrue: [ | m zsMappings |
+	(src treeSize < self sizeThreshold or: [dest treeSize < self sizeThreshold]) ifTrue: [ | m zsMappings |
 		m := DCZhangShashaMatcher new.
 		zsMappings := DCMappingStore new.
 		m matchFrom: src to: dest in: zsMappings.
@@ -44,13 +44,13 @@ DCGreedyBottomUpMatcher >> lastChanceMatchFrom: src to: dest in: aMapping [
 DCGreedyBottomUpMatcher >> matchFrom: src to: dest in: aMapping [
 
 	rootDest := dest.
-	src allMorphsDo: [:t |
+	src allChildrenDo: [:t |
 		src = t
 			ifTrue: [
 				aMapping addMappingFrom: t to: dest.
 				self lastChanceMatchFrom: t to: dest in: aMapping]
 			ifFalse: [
-				((aMapping isSrcMapped: t) not or: [t hasSubmorphs not]) ifTrue: [
+				((aMapping isSrcMapped: t) not or: [t hasChildren not]) ifTrue: [
 					(((self destCandidatesFor: t in: aMapping) select: [:candidate | (DCMappingComparator diceSimilarityFrom: t to: candidate in: aMapping) >= self similarityThreshold]) detectMax: [:candidate | DCMappingComparator diceSimilarityFrom: t to: candidate in: aMapping]) ifNotNil: [:best |
 						self lastChanceMatchFrom: t to: best in: aMapping.
 						aMapping addMappingFrom: t to: best]]]]
diff --git a/packages/DomainCode-Diff/DCGreedySubtreeMatcher.class.st b/packages/DomainCode-Diff/DCGreedySubtreeMatcher.class.st
index 071fd18..bee1dcd 100644
--- a/packages/DomainCode-Diff/DCGreedySubtreeMatcher.class.st
+++ b/packages/DomainCode-Diff/DCGreedySubtreeMatcher.class.st
@@ -17,9 +17,9 @@ DCGreedySubtreeMatcher >> handleAmbiguousMappings: aCollection for: aMapping [
 		mappingStore: aMapping.
 	
 	aCollection sort: [:m1 :m2 | | s1 s2 |
-		s1 := m1 first detectMax: [:t | t recursiveSubmorphCount].
-		s2 := m2 first detectMax: [:t | t recursiveSubmorphCount].
-		s1 recursiveSubmorphCount < s2 recursiveSubmorphCount].
+		s1 := m1 first detectMax: [:t | t treeSize].
+		s2 := m2 first detectMax: [:t | t treeSize].
+		s1 treeSize < s2 treeSize].
 	
 	aCollection do: [:entry | | candidates |
 		candidates := Array streamContents: [:s | entry first do: [:src | entry second do: [:dest | s nextPut: {src. dest}]]].
diff --git a/packages/DomainCode-Diff/DCLeftOverLeafMatcher.class.st b/packages/DomainCode-Diff/DCLeftOverLeafMatcher.class.st
index e98a502..d7f32d7 100644
--- a/packages/DomainCode-Diff/DCLeftOverLeafMatcher.class.st
+++ b/packages/DomainCode-Diff/DCLeftOverLeafMatcher.class.st
@@ -17,9 +17,9 @@ DCLeftOverLeafMatcher >> handleAmbiguousMappings: aCollection for: aMapping [
 		mappingStore: aMapping.
 	
 	aCollection sort: [:m1 :m2 | | s1 s2 |
-		s1 := m1 first detectMax: [:t | t recursiveSubmorphCount].
-		s2 := m2 first detectMax: [:t | t recursiveSubmorphCount].
-		s1 recursiveSubmorphCount < s2 recursiveSubmorphCount].
+		s1 := m1 first detectMax: [:t | t treeSize].
+		s2 := m2 first detectMax: [:t | t treeSize].
+		s1 treeSize < s2 treeSize].
 	
 	aCollection do: [:entry | | candidates |
 		candidates := Array streamContents: [:s | entry first do: [:src | entry second do: [:dest | s nextPut: {src. dest}]]].
@@ -37,10 +37,10 @@ DCLeftOverLeafMatcher >> matchFrom: src to: dest in: aMapping [
 	ambiguousMappings := OrderedCollection new.
 	srcTrees := DCPriorityTreeQueue new
 		minimumHeight: 0;
-		addAll: (Array streamContents: [:s | src allMorphsDo: [:k | (aMapping isSrcMapped: k) ifFalse: [s nextPut: k]]]).
+		addAll: (Array streamContents: [:s | src allChildrenDo: [:k | (aMapping isSrcMapped: k) ifFalse: [s nextPut: k]]]).
 	destTrees := DCPriorityTreeQueue new
 		minimumHeight: 0;
-		addAll: (Array streamContents: [:s | dest allMorphsDo: [:k | (aMapping isDestMapped: k) ifFalse: [s nextPut: k]]]).
+		addAll: (Array streamContents: [:s | dest allChildrenDo: [:k | (aMapping isDestMapped: k) ifFalse: [s nextPut: k]]]).
 	
 	[
 		self synchronizePriority: srcTrees with: destTrees.
diff --git a/packages/DomainCode-Diff/DCMappingComparator.class.st b/packages/DomainCode-Diff/DCMappingComparator.class.st
index fe38282..1640852 100644
--- a/packages/DomainCode-Diff/DCMappingComparator.class.st
+++ b/packages/DomainCode-Diff/DCMappingComparator.class.st
@@ -24,8 +24,8 @@ DCMappingComparator class >> diceSimilarityFrom: src to: dest in: aMapping [
 
 	^ self
 		diceCoefficientCommon: (self numberOfMappedDescendantsFrom: src to: dest in: aMapping)
-		left: src recursiveSubmorphCount - 1
-		right: dest recursiveSubmorphCount - 1
+		left: src treeSize - 1
+		right: dest treeSize - 1
 ]
 
 { #category : #'as yet unclassified' }
diff --git a/packages/DomainCode-Diff/DCMappingStore.class.st b/packages/DomainCode-Diff/DCMappingStore.class.st
index 856518a..38f57e0 100644
--- a/packages/DomainCode-Diff/DCMappingStore.class.st
+++ b/packages/DomainCode-Diff/DCMappingStore.class.st
@@ -11,10 +11,6 @@ Class {
 { #category : #'as yet unclassified' }
 DCMappingStore >> addMappingFrom: src to: dest [
 
-	SBToggledCode
-		comment: ''
-		active: 1
-		do: {[src type = 'lexical_declaration' ifTrue: [self halt]]}.
 	srcToDest at: src put: dest.
 	destToSrc at: dest put: src
 ]
@@ -23,7 +19,7 @@ DCMappingStore >> addMappingFrom: src to: dest [
 DCMappingStore >> addRecursiveMappingFrom: src to: dest [
 
 	self addMappingFrom: src to: dest.
-	src submorphs with: dest submorphs do: [:a :b | self addRecursiveMappingFrom: a to: b]
+	src children with: dest children do: [:a :b | self addRecursiveMappingFrom: a to: b]
 ]
 
 { #category : #'as yet unclassified' }
diff --git a/packages/DomainCode-Diff/DCMatchTest.class.st b/packages/DomainCode-Diff/DCMatchTest.class.st
index 8ac6c8a..1fe67d6 100644
--- a/packages/DomainCode-Diff/DCMatchTest.class.st
+++ b/packages/DomainCode-Diff/DCMatchTest.class.st
@@ -8,10 +8,9 @@ Class {
 DCMatchTest >> testAppendBinary [
 
 	| src dest |
-	Transcript clear.
 	src := DCBlock parseBlock: 'a' language: SBJavascript.
 	dest := DCBlock parseBlock: 'a+' language: SBJavascript.
-	DCMatcher new matchFrom: src to: dest.
+	DCMatcher new applyEditsIn: dest to: src.
 	self assert: 'a+' equals: src sourceString
 ]
 
@@ -19,9 +18,8 @@ DCMatchTest >> testAppendBinary [
 DCMatchTest >> testSplitBinary [
 
 	| src dest |
-	Transcript clear.
 	src := DCBlock parseBlock: 'a2' language: SBJavascript.
 	dest := DCBlock parseBlock: 'a+2' language: SBJavascript.
-	DCMatcher new matchFrom: src to: dest.
+	DCMatcher new applyEditsIn: dest to: src.
 	self assert: 'a+2' equals: src sourceString
 ]
diff --git a/packages/DomainCode-Diff/DCMatcher.class.st b/packages/DomainCode-Diff/DCMatcher.class.st
index 7a36985..b1d0cee 100644
--- a/packages/DomainCode-Diff/DCMatcher.class.st
+++ b/packages/DomainCode-Diff/DCMatcher.class.st
@@ -47,10 +47,10 @@ DCMatcher >> fineGrainedMatch2From: src to: dest in: aMapping [
 
 	| topSrc topDest |
 	topSrc := self
-		commonAncestorOf: (Array streamContents: [:s | src allMorphsDo: [:k | (aMapping isSrcMapped: k) ifFalse: [s nextPut: k]]])
+		commonAncestorOf: (Array streamContents: [:s | src allChildrenDo: [:k | (aMapping isSrcMapped: k) ifFalse: [s nextPut: k]]])
 		root: src.
 	topDest := self
-		commonAncestorOf: (Array streamContents: [:s | dest allMorphsDo: [:k | (aMapping isDestMapped: k) ifFalse: [s nextPut: k]]])
+		commonAncestorOf: (Array streamContents: [:s | dest allChildrenDo: [:k | (aMapping isDestMapped: k) ifFalse: [s nextPut: k]]])
 		root: dest.
 	(topSrc notNil and: [topDest notNil]) ifTrue: [
 		"see if we can answer quickly, otherwise we accept a worse diff result"
@@ -66,8 +66,8 @@ DCMatcher >> fineGrainedMatch2From: src to: dest in: aMapping [
 DCMatcher >> fineGrainedMatchFrom: src to: dest in: aMapping [
 
 	| topSrc topDest |
-	topSrc := (Array streamContents: [:s | src allMorphsDo: [:k | (aMapping isSrcMapped: k) ifFalse: [s nextPut: k]]]) detectMax: #treeHeight.
-	topDest := (Array streamContents: [:s | dest allMorphsDo: [:k | (aMapping isDestMapped: k) ifFalse: [s nextPut: k]]]) detectMax: #treeHeight.
+	topSrc := (Array streamContents: [:s | src allChildrenDo: [:k | (aMapping isSrcMapped: k) ifFalse: [s nextPut: k]]]) detectMax: #treeHeight.
+	topDest := (Array streamContents: [:s | dest allChildrenDo: [:k | (aMapping isDestMapped: k) ifFalse: [s nextPut: k]]]) detectMax: #treeHeight.
 	
 	self halt.
 	topSrc ifNotNil: [
@@ -80,7 +80,7 @@ DCMatcher >> fineGrainedMatchFrom: src to: dest in: aMapping [
 { #category : #'as yet unclassified' }
 DCMatcher >> largestUnmappedFor: aTree isSrc: aBoolean in: aMapping [
 
-	^ (Array streamContents: [:s | aTree allMorphsDo: [:k | (aBoolean ifTrue: [aMapping isSrcMapped: k] ifFalse: [aMapping isDestMapped: k]) ifFalse: [s nextPut: k]]]) detectMax: #treeHeight
+	^ (Array streamContents: [:s | aTree allChildrenDo: [:k | (aBoolean ifTrue: [aMapping isSrcMapped: k] ifFalse: [aMapping isDestMapped: k]) ifFalse: [s nextPut: k]]]) detectMax: #treeHeight
 ]
 
 { #category : #'as yet unclassified' }
diff --git a/packages/DomainCode-Diff/DCPriorityTreeQueue.class.st b/packages/DomainCode-Diff/DCPriorityTreeQueue.class.st
index ff5d9bc..e37f7f3 100644
--- a/packages/DomainCode-Diff/DCPriorityTreeQueue.class.st
+++ b/packages/DomainCode-Diff/DCPriorityTreeQueue.class.st
@@ -23,7 +23,7 @@ DCPriorityTreeQueue >> addAll: aCollection [
 { #category : #'as yet unclassified' }
 DCPriorityTreeQueue >> addTree: tree [
 
-	tree submorphs do: [:child | self add: child]
+	tree children do: [:child | self add: child]
 ]
 
 { #category : #'as yet unclassified' }
diff --git a/packages/DomainCode-Diff/DCZhangShashaTree.class.st b/packages/DomainCode-Diff/DCZhangShashaTree.class.st
index 9e91952..f3838d1 100644
--- a/packages/DomainCode-Diff/DCZhangShashaTree.class.st
+++ b/packages/DomainCode-Diff/DCZhangShashaTree.class.st
@@ -15,18 +15,18 @@ Class {
 DCZhangShashaTree >> for: aTree [
 
 	| index tmpData visited k |
-	nodeCount := aTree recursiveSubmorphCount.
+	nodeCount := aTree treeSize.
 	leafCount := 0.
 	llds := Array new: nodeCount.
 	labels := Array new: nodeCount.
 	
 	index := 1.
 	tmpData := Dictionary new.
-	aTree allMorphsDo: [:n |
+	aTree allChildrenDo: [:n |
 		tmpData at: n put: index.
 		labels at: index put: n.
-		llds at: index put: (tmpData at: n firstDeepSubmorph) - 1.
-		n hasSubmorphs ifFalse: [leafCount := leafCount + 1].
+		llds at: index put: (tmpData at: n firstDeepChildNode) - 1.
+		n hasChildren ifFalse: [leafCount := leafCount + 1].
 		index := index + 1].
 	
 	keyRoots := Array new: leafCount + 1.
diff --git a/packages/DomainCode-Parser/DCBlock.class.st b/packages/DomainCode-Parser/DCBlock.class.st
index 5b85811..4dda76a 100644
--- a/packages/DomainCode-Parser/DCBlock.class.st
+++ b/packages/DomainCode-Parser/DCBlock.class.st
@@ -72,6 +72,14 @@ DCBlock class >> fromCursor: aCursor language: aLanguage [
 				range: aCursor range]
 ]
 
+{ #category : #generic }
+DCBlock class >> genericAddMarker [
+	<query: #shortcut>
+
+	^ {
+		[:x | x registerShortcut: #addMarker do: [{[:block | block attachDecorator: SBMarkedDecorator new]}]]}
+]
+
 { #category : #'as yet unclassified' }
 DCBlock class >> parse: aString language: aLanguage [
 
@@ -132,7 +140,8 @@ DCBlock class >> registerShortcuts: aProvider [
 	aProvider cmdShortcut: $[ do: #wrapInSquareBrackets.
 	aProvider cmdShortcut: $' do: #wrapInSingleQuotes.
 	aProvider cmdShortcut: $" do: #wrapInDoubleQuotes.
-	aProvider cmdShortcut: $` do: #wrapInBackticks
+	aProvider cmdShortcut: $` do: #wrapInBackticks.
+	aProvider shortcut: $M command do: #addMarker
 ]
 
 { #category : #smalltalk }
@@ -181,6 +190,20 @@ DCBlock class >> smalltalkBrowseReferencesSend [
 							ifFalse: [message sandblockEditor open: calls first compiledMethod]]}]]}
 ]
 
+{ #category : #smalltalk }
+DCBlock class >> smalltalkCheckbox [
+	<query: #change>
+
+	^ {
+		[:x | x language = SBTSSmalltalk].
+		[:x | x isReplacement not].
+		[:x | {#true. #false} includes: x type].
+		[:x |
+			x installReplacement: (DCCheckbox new
+				fromSource: [:source :repl | repl checked: source contents = 'true']
+				toSource: [:source :repl | source contents: (repl checked ifTrue: ['true'] ifFalse: ['false'])])]}
+]
+
 { #category : #smalltalk }
 DCBlock class >> smalltalkDeclaration [
 
@@ -267,7 +290,7 @@ DCBlock class >> smalltalkUndeclaredVariable [
 									container: temporaries;
 									index: temporaries submorphCount)]
 							ifNone: [ | index |
-								index := block submorphs findFirst: [:s | s treeLabel = '|'].
+								index := block children findFirst: [:s | s treeLabel = '|'].
 								node sandblockEditor do: (SBInsertCommand new
 									morph: (DCBlock new
 										type: #temporaries;
@@ -297,9 +320,12 @@ DCBlock class >> smalltalkUnusedVariable [
 DCBlock class >> smalltalkUsesOfDeclaration [
 
 	^ {
-		[:decl | {#args. decl. decl orAnyParent: #(block method)}].
-		[:decl :scope | {#args. decl. scope allBlocksSelect: [:x | (#(identifier block_argument) includes: x type) and: [(x contents withoutLeading: #($:)) = (decl contents withoutLeading: #($:))]]}]
-	}
+		[:decl | {#args. decl. decl orAnyParent: #(#block #method)}].
+		[:decl :scope |
+			{
+				#args.
+				decl.
+				scope allChildrenSelect: [:x | (#(#identifier #'block_argument') includes: x type) and: [(x contents withoutLeading: #($:)) = (decl contents withoutLeading: #($:))]]}]}
 ]
 
 { #category : #'as yet unclassified' }
@@ -307,7 +333,7 @@ DCBlock >> absolutePositionOf: aMorph [
 
 	| n |
 	n := 0.
-	self allMorphsDo: [:m |
+	self allChildrenDo: [:m |
 		n := n + 1.
 		m = aMorph ifTrue: [^ n]].
 	^ self assert: false
@@ -365,7 +391,7 @@ DCBlock >> allParentsUpTo: aBlock [
 { #category : #'as yet unclassified' }
 DCBlock >> allTextMorphsDo: aBlock [
 
-	self allMorphsDo: [:m | m isTextMorph ifTrue: [aBlock value: m]]
+	self allChildrenDo: [:m | m isTextMorph ifTrue: [aBlock value: m]]
 ]
 
 { #category : #'as yet unclassified' }
@@ -383,7 +409,7 @@ DCBlock >> attachHighlight [
 { #category : #'as yet unclassified' }
 DCBlock >> blockFor: aRange [
 
-	self allMorphsDo: [:block | (block isTSMorph and: [block range = aRange]) ifTrue: [^ block]].
+	self allChildrenDo: [:block | (block isTSMorph and: [block range = aRange]) ifTrue: [^ block]].
 	^ nil
 ]
 
@@ -403,7 +429,7 @@ DCBlock >> contentsToDisplay [
 DCBlock >> copyRangesFrom: newTree to: oldTree [
 
 	oldTree range: newTree range.
-	newTree submorphs with: oldTree submorphs do: [:a :b | self copyRangesFrom: a to: b]
+	newTree children with: oldTree children do: [:a :b | self copyRangesFrom: a to: b]
 ]
 
 { #category : #'as yet unclassified' }
@@ -494,7 +520,7 @@ DCBlock >> findLastMatchingAncesors: aCollection oldTree: aBlock [
 	| oldCurrent |
 	oldCurrent := aBlock.
 	aCollection allButLast reverseDo: [:newCurrent |
-		oldCurrent := oldCurrent submorphs at: newCurrent submorphIndex ifAbsent: [
+		oldCurrent := oldCurrent children at: newCurrent submorphIndex ifAbsent: [
 			self assert: oldCurrent type = newCurrent owner type.
 			^ {oldCurrent. newCurrent owner}].
 		oldCurrent type = newCurrent type ifFalse: [
@@ -618,7 +644,7 @@ DCBlock >> inputClosestTextMorphTo: cursorPosition [
 	atStart := false.
 	
 	"match on same line"
-	self allMorphsDo: [:t |
+	self allChildrenDo: [:t |
 		t isTextMorph ifTrue: [
 			t range start line = cursorPosition line ifTrue: [ | distance |
 				distance := (t range start character - cursorPosition character) abs.
@@ -635,7 +661,7 @@ DCBlock >> inputClosestTextMorphTo: cursorPosition [
 	
 	"match on different line"
 	best ifNil: [
-		self allMorphsDo: [:t |
+		self allChildrenDo: [:t |
 			t isTextMorph ifTrue: [ | distance |
 				distance := (t range start line - cursorPosition line) abs min: (t range end line - cursorPosition line) abs.
 				distance < bestDistance ifTrue: [
@@ -690,6 +716,12 @@ DCBlock >> insertStatementHasCandidate [
 	^ true
 ]
 
+{ #category : #'as yet unclassified' }
+DCBlock >> installReplacement: aBlock [
+
+	self sandblockEditor do: (SBReplaceCommand new target: self replacer: (aBlock source: self))
+]
+
 { #category : #'as yet unclassified' }
 DCBlock >> intoWorld: aWorld [
 
@@ -699,7 +731,8 @@ DCBlock >> intoWorld: aWorld [
 		self sandblockEditor
 			when: #selectionChanged
 			send: #updateSelectionQueries
-			to: self queryState]
+			to: self queryState.
+		self queryState updateChangeQueries]
 ]
 
 { #category : #'as yet unclassified' }
@@ -730,6 +763,12 @@ DCBlock >> isPart [
 	^ self highlight notNil and: [self highlight endsWith: '.part']
 ]
 
+{ #category : #'as yet unclassified' }
+DCBlock >> isReplacement [
+
+	^ false
+]
+
 { #category : #'as yet unclassified' }
 DCBlock >> isRootBlock [
 
@@ -949,7 +988,7 @@ DCBlock >> printOn: aStream [
 DCBlock >> queryAll: aString [
 
 	^ Array streamContents: [:stream |
-		self allMorphsDo: [:block |
+		self allChildrenDo: [:block |
 			block isTSMorph ifTrue: [
 				(SBTSQuery new
 					prepare: aString;
@@ -1143,7 +1182,7 @@ DCBlock >> template [
 { #category : #'as yet unclassified' }
 DCBlock >> textMorphForPosition: aPosition [
 
-	self allMorphsDo: [:t | (t isTextMorph and: [t range contains: aPosition]) ifTrue: [^ t]].
+	self allChildrenDo: [:t | (t isTextMorph and: [t range contains: aPosition]) ifTrue: [^ t]].
 	^ nil
 ]
 
@@ -1156,8 +1195,8 @@ DCBlock >> textMorphs [
 { #category : #'as yet unclassified' }
 DCBlock >> treeHash [
 
-	self hasSubmorphs ifFalse: [^ self treeHashChildren: 0].
-	^ self treeHashChildren: (self submorphs inject: 0 into: [:hash :morph | hash bitXor: morph treeHash])
+	self hasChildren ifFalse: [^ self treeHashChildren: 0].
+	^ self treeHashChildren: (self children inject: 0 into: [:hash :morph | hash bitXor: morph treeHash])
 ]
 
 { #category : #'as yet unclassified' }
diff --git a/packages/DomainCode-Parser/DCCheckbox.class.st b/packages/DomainCode-Parser/DCCheckbox.class.st
new file mode 100644
index 0000000..c0af22c
--- /dev/null
+++ b/packages/DomainCode-Parser/DCCheckbox.class.st
@@ -0,0 +1,25 @@
+Class {
+	#name : #DCCheckbox,
+	#superclass : #DCReplacement,
+	#category : #'DomainCode-Parser'
+}
+
+{ #category : #'as yet unclassified' }
+DCCheckbox >> checked [
+
+	^ self firstSubmorph value
+]
+
+{ #category : #'as yet unclassified' }
+DCCheckbox >> checked: aBoolean [
+
+	self firstSubmorph value: aBoolean
+]
+
+{ #category : #'as yet unclassified' }
+DCCheckbox >> initialize [
+
+	super initialize.
+	
+	self addMorphBack: SBCheckbox new
+]
diff --git a/packages/DomainCode-Parser/DCMockSlot.class.st b/packages/DomainCode-Parser/DCMockSlot.class.st
index eb7de46..e08a38e 100644
--- a/packages/DomainCode-Parser/DCMockSlot.class.st
+++ b/packages/DomainCode-Parser/DCMockSlot.class.st
@@ -154,8 +154,8 @@ DCMockSlot >> type [
 DCMockSlot >> updateAllHighlightsFor: aBlock [
 
 	morph language instance grammar hasHighlight ifFalse: [^ #'_sb_none'].
-	aBlock allMorphsDo: [:m | m isTSMorph ifTrue: [m highlight: #'_sb_none']].
-	aBlock allMorphsBreadthFirstDo: [:m | m isTSMorph ifTrue: [m slot updateHighlightFor: m]].
+	aBlock allChildrenDo: [:m | m isTSMorph ifTrue: [m highlight: #'_sb_none']].
+	aBlock allChildrenBreadthFirstDo: [:m | m isTSMorph ifTrue: [m slot updateHighlightFor: m]].
 	^ aBlock highlight
 ]
 
diff --git a/packages/DomainCode-Parser/DCReplacement.class.st b/packages/DomainCode-Parser/DCReplacement.class.st
new file mode 100644
index 0000000..154fe4f
--- /dev/null
+++ b/packages/DomainCode-Parser/DCReplacement.class.st
@@ -0,0 +1,92 @@
+Class {
+	#name : #DCReplacement,
+	#superclass : #DCBlock,
+	#instVars : [
+		'source',
+		'bindings'
+	],
+	#category : #'DomainCode-Parser'
+}
+
+{ #category : #'as yet unclassified' }
+DCReplacement >> children [
+
+	^ self source children
+]
+
+{ #category : #'as yet unclassified' }
+DCReplacement >> fromSource: aBlock toSource: anotherBlock [
+
+	bindings add: aBlock -> anotherBlock
+]
+
+{ #category : #'as yet unclassified' }
+DCReplacement >> initialize [
+
+	super initialize.
+	bindings := OrderedCollection new
+]
+
+{ #category : #'as yet unclassified' }
+DCReplacement >> isNode: aNode [
+
+	^ self source = aNode
+]
+
+{ #category : #'as yet unclassified' }
+DCReplacement >> isReplacement [
+
+	^ true
+]
+
+{ #category : #'as yet unclassified' }
+DCReplacement >> layoutCommands [
+
+	^ SBAlgebraCommand container
+		morph: self;
+		data: (self submorphs collect: [:s | s layoutCommands] separatedBy: [SBAlgebraCommand softLine])
+]
+
+{ #category : #'as yet unclassified' }
+DCReplacement >> source [
+
+	^ source
+]
+
+{ #category : #'as yet unclassified' }
+DCReplacement >> source: aBlock [
+
+	source := aBlock.
+	bindings do: [:assoc | assoc key value: self source value: self]
+]
+
+{ #category : #'as yet unclassified' }
+DCReplacement >> treeHash [
+
+	^ self source treeHash
+]
+
+{ #category : #'as yet unclassified' }
+DCReplacement >> treeLabel [
+
+	^ self source treeLabel
+]
+
+{ #category : #'as yet unclassified' }
+DCReplacement >> type [
+
+	^ self source type
+]
+
+{ #category : #'as yet unclassified' }
+DCReplacement >> updateSourceDuring: aBlock [
+
+	bindings do: [:assoc | assoc value value: self source value: self].
+	aBlock value
+]
+
+{ #category : #'as yet unclassified' }
+DCReplacement >> writeSourceOn: aStream indent: aNumber forCompare: aBoolean [
+
+	self updateSourceDuring: [self source writeSourceOn: aStream indent: aNumber forCompare: aBoolean]
+]