Lex and I just found a little discrepancy in UpdatingStringMorph's
behavior: it cannot be picked up because its #handlesMouseDown:
doesn't check if there is the putSelector. Here's a proposed fix:

handlesMouseDown: evt
    putSelector ifNil: [^false].
    (owner wantsKeyboardFocusFor: self)
        ifTrue:
            [^ self uncoveredAt: evt cursorPoint].
    ^ super handlesMouseDown: evt

(the change is addition of the first line).

Bolot