In nautilus I get an error MNU: RBBlockNode>>method When I select several groups and select merge mergeGroups: aCollection aCollection ifNotEmpty: [:groups || group | group := groups reduce: [:a :b | a or: [b]]. ^^^^^^^^^^^^ a is a dynamicClassGroup and its superclass defines or: groups do: [:gp | gp removable ifTrue: [self groupsManager removeAGroupSilently: gp]]. ^ group]. ^ nil RBBlockNode(Object)>>doesNotUnderstand: #method RBBlockNode>>sourceNodeForPC: DynamicClassGroup(Object)>>mustBeBooleanInMagic: DynamicClassGroup(Object)>>mustBeBoolean [ :a :b | a or: [ b ] ] in [ :groups | | group | group := groups reduce: [ :a :b | a or: [ b ] ]. groups do: [ :gp | gp removable ifTrue: [ self groupsManager removeAGroupSilently: gp ] ]. ^ group ] in PackageTreeNautilusUI(AbstractTool)>>mergeGroups: in Block: [ :a :b | a or: [ b ] ] [ :index | arguments replaceFrom: 2 to: arguments size with: self startingAt: index; at: 1 put: (aBlock valueWithArguments: arguments) ] in Array(SequenceableCollection)>>reduceLeft: in Block: [ :index | ... SmallInteger(Number)>>to:by:do: Array(SequenceableCollection)>>reduceLeft: Array(SequenceableCollection)>>reduce: [ :groups | | group | group := groups reduce: [ :a :b | a or: [ b ] ]. groups do: [ :gp | gp removable ifTrue: [ self groupsManager removeAGroupSilently: gp ] ]. ^ group ] in PackageTreeNautilusUI(AbstractTool)>>mergeGroups: in Block: [ :groups | ... BlockClosure>>cull: Array(Collection)>>ifNotEmpty: PackageTreeNautilusUI(AbstractTool)>>mergeGroups: PackageTreeNautilusUI(AbstractNautilusUI)>>mergeGroups [ target mergeGroups ] in AbstractNautilusUI class>>groupsMenu: in Block: [ target mergeGroups ] BlockClosure>>cull: [ | selArgCount | "show cursor in case item opens a new MVC window" (selArgCount := selector numArgs) = 0 ifTrue: [ target perform: selector ] ifFalse: [ selArgCount = arguments size ifTrue: [ target perform: selector withArguments: arguments ] ifFalse: [ target perform: selector withArguments: (arguments copyWith: evt) ] ]. self changed ] in ToggleMenuItemMorph(MenuItemMorph)>>invokeWithEvent: in Block: [ ... BlockClosure>>ensure: CursorWithMask(Cursor)>>showWhile: ToggleMenuItemMorph(MenuItemMorph)>>invokeWithEvent: ToggleMenuItemMorph(MenuItemMorph)>>mouseUp: ToggleMenuItemMorph(MenuItemMorph)>>handleMouseUp: MouseButtonEvent>>sentTo: ToggleMenuItemMorph(Morph)>>handleEvent: MorphicEventDispatcher>>dispatchDefault:with: MorphicEventDispatcher>>handleMouseUp: MouseButtonEvent>>sentTo: [ ^ anEvent sentTo: self ] in MorphicEventDispatcher>>dispatchEvent:with: in Block: [ ^ anEvent sentTo: self ] BlockClosure>>ensure: MorphicEventDispatcher>>dispatchEvent:with: