Chris Muller uploaded a new version of ToolBuilder-Morphic to project The Trunk: http://source.squeak.org/trunk/ToolBuilder-Morphic-cmm.154.mcz
==================== Summary ====================
Name: ToolBuilder-Morphic-cmm.154 Author: cmm Time: 22 December 2015, 3:33:18.425 pm UUID: 9c0f9cf0-1b21-448f-8401-f69edc04e17e Ancestors: ToolBuilder-Morphic-mt.153
Encountered the model already nil'd out before entering PluggableSystemWindow>>#delete on occasion. Protect against that.
=============== Diff against ToolBuilder-Morphic-mt.153 ===============
Item was changed: ----- Method: PluggableSystemWindow>>delete (in category 'initialization') ----- delete + (model notNil and: [ closeWindowSelector notNil ]) ifTrue: [ model perform: closeWindowSelector ]. + super delete! - closeWindowSelector ifNotNil:[model perform: closeWindowSelector]. - super delete. - !