Hi, RubScrolledTextModel fails sometimes if the model does not have an interaction model set. For example in a few places there is a check that verifies if the model understands a message and then the message is send to the interaction model. evaluate: aStream andDo: aBlock .... (self model respondsTo: #doItReceiver) "check on the model" ifTrue: [ rcvr := self model doItReceiver. ctxt := self model doItContext] And then doItReceiver is implemented like: doItReceiver ^ interactionModel ifNotNil: [ :im | im doItReceiver ] "message send to the interaction model" Also in some cases a condition is checked on the model and then the actual result is obtained from the interaction model: (self model systemNavigation allImplementorsOf: aSelector) isEmpty ifTrue: [ self internalCallToBrowse: aSelector ] ifFalse: [ self model interactionModel systemNavigation browseAllImplementorsOf: aSelector ] I'll say these are bugs. Also should a RubScrolledTextModel always have an interaction model? Cheers, Andrei