I am trying to look into this issue in Glamour related to morphs: http://code.google.com/p/pharo/issues/detail?id=7345 The problem is that, in Glamour, one can choose to display first few items instead of the all and then the user can choose to display more. When the selection is set to the items not shown, there is a DNU in PaginatedMorphTreeMorph. Digging this problem, I have encountered this piece of code for which I would require the help of someone knowing Morph. Is someone knowledgable about this piece of code? Here you can find an image with the script to explore the problem: https://dl.dropbox.com/u/11804892/glamour-treemorphs.zip MorphTreeMorph >> update: update: aSymbol aSymbol == #selection ifTrue: [^ self listManager updateSelectionFromModel]. ((aSymbol isKindOf: Array) and: [aSymbol size > 1 and: [aSymbol first == #selectItems and: [aSymbol second isCollection]]]) ifTrue: [^ self selectedItems: aSymbol second]. aSymbol == self nodeListSelector ifTrue: [^ self updateList]. aSymbol == #selectAll ifTrue: [^ self listManager selectAll]. aSymbol == #deselectAll ifTrue: [^ self listManager deselectAll]. ((aSymbol isKindOf: Array) and: [aSymbol size > 1 and: [aSymbol first == self nodeListSelector and: [ aSymbol second == #openPath]]]) "allow directed path opening where multiple trees exist" ifTrue: [^(self allNodeMorphs at: 1 ifAbsent: [^self]) openPath: (aSymbol allButFirst: 2)]. ((aSymbol isKindOf: Array) and: [aSymbol size > 1 and: [aSymbol first == self nodeListSelector and: [ aSymbol second == #openItemPath]]]) "allow directed path opening where multiple trees exist" ifTrue: [^ (self allNodeMorphs at: 1 ifAbsent: [^self]) openItemPath: (aSymbol allButFirst: 2)]. ((aSymbol isKindOf: Array) and: [aSymbol size > 1 and: [aSymbol first == self nodeListSelector and: [ aSymbol second == #expandAllFromNode:]]]) ifTrue: [^ self expandAllFromNode: aSymbol third]. ((aSymbol isKindOf: Array) and: [aSymbol size > 1 and: [aSymbol first == self nodeListSelector and: [ aSymbol second == #closeItemPath]]]) "allow directed path closing where multiple trees exist" ifTrue: [^ (self allNodeMorphs at: 1 ifAbsent: [^self]) closeItemPath: (aSymbol allButFirst: 2)]. ((aSymbol isKindOf: Array) and: [aSymbol notEmpty and: [aSymbol first == #openPath]]) ifTrue: [^(self allNodeMorphs at: 1 ifAbsent: [^self]) openPath: aSymbol allButFirst]. ((aSymbol isKindOf: Array) and: [aSymbol size = 2 and: [aSymbol first = self nodeListSelector and: [ aSymbol second == #expandRoots]]]) ifTrue: [^self expandRoots]. ((aSymbol isKindOf: Array) and: [aSymbol size = 2 and: [aSymbol first = self nodeListSelector]]) ifTrue: [aSymbol second = #expandAll ifTrue: [^ self expandAll]. aSymbol second = #collapseAll ifTrue: [^ self collapseAll]]