Magritte validation problem with MABooleanDescription

Hi, I've been struggling with a Magritte validation problem. I find that a condition I add (using #addCondition:labelled:) to a MABooleanDescription is only intermittently called. I've simplified the conditions to reproduce the problem to a component description comprising of two MABooleanDescription descriptions. The second description includes the condition which is intermittently called. If the value of the first description is true (ie the checkbox is checked) the second description's condition will be executed, however if it is false it will never be executed. I suspect the problems lies in the code in MAValidatorVisitor>>#visitContainer: which calls MAGraphVisitor>>#use:during: which is as follows: MAGraphVisitor >>use: anObject during: aBlock | previous | (seen includes: anObject) ifTrue: [ ^ self ]. anObject isNil ifFalse: [ seen add: anObject ]. previous := object. object := anObject. aBlock ensure: [ object := previous ] If the first check box is false, and the second is also false then (seen includes: anObject) will return true and method returns early resulting in block associated with second description (self visit: description) never being executed. I've attached a file out of a simple component TestMagritteValidation illustrating the problem that I tested in the latest build from Hudson. Thanks Nick