Smalltalk createPackage: 'Helios-Exceptions'! Error subclass: #HLError slots: {} package: 'Helios-Exceptions'! !HLError commentStamp! I am the abstract superclass of all Helios-specific errors.! HLError subclass: #HLChangeForbidden slots: {} package: 'Helios-Exceptions'! !HLChangeForbidden commentStamp! I get signaled when a (often user) requested change is forbidden. A confirmation message can then be displayed to the user. See `HLModel >> withChangesDo:`.! HLError subclass: #HLListItemNotFound slots: {} package: 'Helios-Exceptions'! !HLListItemNotFound commentStamp! I get signaled by a `HLListWidget` when a non-existing item in the list is activated.!