Concurrency problem when element is exported to Form while its space is opened

This can happen when a script in a Workspace creates an element in a space, sends show it it, and immediately sends inspect to the element.

The inspector preview tab for element defined in:

BlElement >>
inspectionPreview: aBuilder
    <inspectorPresentationOrder: 1 title: 'Preview'>

    ^ aBuilder newMorph
        morph: self asPreviewMorph;
        yourself

ends up executing this:

BlElement >>
aeAsForm

    | invalidationBounds aCanvas |
    self isLayoutRequested ifTrue: [ self forceLayout ].

    "We want to consider our border, effect, as well as children's."
    invalidationBounds := self invalidationBoundsInSpace.
    aCanvas := AeCanvas extent: invalidationBounds extent.
    aCanvas pathTranslate: invalidationBounds origin negated.
    self aeFullDrawOn: aCanvas.
    ^ aCanvas asForm

This can be seen in this example of Toplo:

ToSandbox >>
example_SelectMaterialDesignIconMultiFiltrable

    | select   |
    select := ToMultiSelectElement new.
    self buildSelectListElementIn: select withIconProvider: ToMaterialDesignIconProvider.

    select filtrable: true.

    select nodeBuilder: [ :node :holder :iconDesc|
        | imPane |
        imPane := ToElement new layout: BlFrameLayout new.
        imPane fitContent.
        imPane withNullSkin.
        imPane background: Color veryLightGray.
        imPane addChild: (iconDesc icon size: 48 asPoint).
        node middleElement: imPane ].
    select fakeDataItem: select dataAccessor first.
    select hMatchParent.
    select placeholderText:
        ('Select icons' asRopedText foreground: Color red).

    select inputTextField requestFocus.
    select openInSpace.
    select inspect

pharo-graphics / Bloc

Concurrency problem when element is exported to Form while its space is opened #560