I've been playing with this, and found that dragging does not
cause squeak to hang, but that double-clicking on the black borders
around the textboxes does.

The following code demonstrates this:

|w f t1 t2 |
w := SystemWindow labelled: 'Ahh Kirsty'.

f := Morph new.
t1 := PluggableTextMorph new.
t2 := PluggableTextMorph new.

w addMorph: f frame: w fullFrame.
f addMorph: t1.
f addMorph: t2.

f layoutPolicy: TableLayout new.
t1 model: w.
t2 model: w.

t1 setText: ''.
t2 setText: ''.


w openInWorld.