Hi All, I've just upgrade from Pharo 60395 to 60411 and am now unable to inspect instances of Matrix. I think I read somewhere that the GTInspector is now using fast tables, and am guessing that it is this change that is causing the problem. I've included code below to reproduce the problem and a stack trace. The sample code creates a 3 x 3 matrix. FTTableContainerMorph>>updateExposedRows suggests that the matrix is being treated as a one-dimensional collection: self owner numberOfRows => 9 "expected 3" self owner numberOfColumns => 1 "expected 3" I'll keep investigating, but if someone more familiar can point me in the right direction, any hints will be appreciated. Thanks, Alistair Pharo 6.0 Latest update: #60411 OS: 4.9.8-1-ARCH | m | m := Matrix rows: 3 columns: 3. 1 to: 3 do: [ :i | 1 to: 3 do: [ :j | m at: i at: j put: 'C', i printString, j printString ] ]. m inspect Matrix(Object)>>error: Matrix(Object)>>errorNotIndexable Matrix(Object)>>at: GLMFastListDataSource(FTSimpleDataSource)>>elementAt: GLMFastListDataSource>>cellColumn:row: FTTableContainerMorph>>updateExposedRows FTTableMorph>>resetPosition FTTableMorph>>resizeAllSubviews FTTableMorph>>extent: FTTableMorph(Morph)>>bounds: FTTableMorph(Morph)>>layoutInBounds: FTTableMorph(Morph)>>layoutProportionallyIn: [ :m | m layoutProportionallyIn: newBounds ] in ProportionalLayout>>layout:in: in Block: [ :m | m layoutProportionallyIn: newBounds ] Array(SequenceableCollection)>>do: GLMPanelMorph(Morph)>>submorphsDo: ProportionalLayout>>layout:in: GLMPanelMorph(Morph)>>doLayoutIn: [ self doLayoutIn: self layoutBounds ] in GLMPanelMorph(Morph)>>computeFullBounds in Block: [ self doLayoutIn: self layoutBounds ] BlockClosure>>on:do: GLMPanelMorph(Morph)>>computeFullBounds GLMPanelMorph(Morph)>>fullBounds [ :m | | subBox | m visible ifTrue: [ subBox := m fullBounds. box ifNil: [ box := subBox copy ] ifNotNil: [ box := box quickMerge: subBox ] ] ] in GLMPanelMorph(Morph)>>submorphBounds in Block: [ :m | ... Array(SequenceableCollection)>>do: GLMPanelMorph(Morph)>>submorphBounds GLMPanelMorph(Morph)>>privateFullBounds GLMPanelMorph(Morph)>>doLayoutIn: [ self doLayoutIn: self layoutBounds ] in GLMPanelMorph(Morph)>>computeFullBounds in Block: [ self doLayoutIn: self layoutBounds ] BlockClosure>>on:do: GLMPanelMorph(Morph)>>computeFullBounds GLMPanelMorph(Morph)>>fullBounds