Based on what you say, from this amended code...

b := ROBox new.
c := ROCircle new.
b addLast: c.
(b removeShape: ROCircle) inspect

 
I would expect to get a chain: aROBox --> aROChildrenShape
but instead I get only: aROChildrenShape
 
Can you confirm that result?  I had played around a bit with the code, but Monticello does currently say Roassal.274 has "no changes"

Alexandre Bergel wrote:

Just recording a bit of my learning the internals of Roassal, since it helps me flesh out my understanding.
[ROShape>>removeShape:] does not have a test to reference for my understanding of this, but it appears to not work as expected. For example in workspace...
b := ROBox new.
c := ROCircle new.
b addLast: c.
b removeShape: ROCircle.
b inspect


removeShape: works as expected I believe. I guess the problem is a matter of naming. 
The method ROShape>>removeShape: is actually an helper method and it is not meant to be directly called.

But without a lot of documentation so far, looking at and understanding the internals does help the external use it (but with the danger of the boundary becoming a bit grey)

Look at the method:
-=-=-=-=-=-=-=-=-=-=-=-=
ROElement>>removeShape: aShapeClass
	"Remove a shape of the element"

	shape := shape removeShape: aShapeClass
-=-=-=-=-=-=-=-=-=-=-=-=

Again, I use the Null Object design pattern. I wanted to loop here on the list of shape and doing a if-statement. 

Actually, ROShape>>removeShape: aShape does not remove a shape, it simply return a collection of shapes without aShape. What a better method name could be? #shapesWithout: or #shapeChainWithout: ?

Perhaps ROShape>>withoutShape:

results in a linked list of: aROBoxShape --> aROCircleShape --> aROChildrenShape. Actually the semantics of [removeShape:] seem problematic. What should be the result of...
b := ROBox new.
b removeShape: ROBox.
b inspect.


The method #removeShape: has indeed a very bad name. It suggests a side effect, but none is actually realized.

I would guess that 'b' should hold aROChildrenShape, except you can't change the value of  'b' from inside the [removeShape:] method.  (In my limited knowledge of 'slots', I wonder if this is something they might help with.) I am relying on the guess that you could have aROChildrenShape as the only shape on an element, for subviews without a border, but could you clarify this. 
Naively I thought to just try... removeShape: aShapeClass
  ^ (self isKindOf: aShapeClass)
      ifTrue: [ next become: next next ]
      ifFalse: [ next removeShape: aShapeClass ]

but the danger of #become hit me and locked my image.

btw, something else just while I am feeling evil, what should happen with the following...
b := ROBox new.
b removeShape: ROChildrenShape.
b inspect.


I guess my answer given above should clear up the things...

Yes, understood, Thanks.

Alexandre