I am not familiar with that part of Pharo because I never use temporary variables in Workspace but I did a little experiment and this is what I found . I followed these 3 steps
1) I created 2 Workspaces��
2) In first Workspace I put the code��
|a|
a:= Morph new.
a openInWindow .
3) In the second Workspace I put the code
a:= Morph new.
a openInWindow .
Now executing both examples give the result you would expect , a morph inside a window BUT if I inspect variable a in both cases , the workspace variable example returns me a Morph as to be expected on the other hand the workspace temporary variable returns me an undefined object. So that leads me to assume here that the temporary variable works as expect by destroying its reference as soon as the code is executed, hence why its called "temporary ;)��