> I have a SystemWindow pane with a PluggableListMorph whose selection
> is never highlighted when I click on a list item.
>
> Each list item understands asString and is properly displayed. The
> PluggableListMorph is definitely firing my model's getListSelector
> and setIndexSelector when I click, but its selectedMorph and
> selection instance variables never get set.
>
And are you sending an appropriate changed: message with the name of
your get index selector?
(assuming the PLM is plugged to these two selectors):
myGetIndexSelector
 ^myIndex
mySetIndexSelector: aNumber
 myIndex := aNumber.
 self changed: #myGetIndexSelector.