If you encounter an error, then you can use Smalltalk's walkback
window to see the receivermessage combinations leading to the error.
If you press the debug button in the walkback window, then you can use
the debugger window to examine the receivermessage
combinations leading to the error and to determine values for
receivers, parameters, and local variables.
If you want to step through an evaluation, then instantiate and
evaluate the following pattern in a workspace:
Object halt.
expression to be stepped through
and then press the hop, skip, and jump buttons. The hop button steps the
least; the skip button steps a little more; and the jump button steps to
the next breakpoint.
If you want to set a breakpoint, then click right > Add Breakpoint
while you are in the debugger.
If you want to determine the senders or implementers of a method with a
given name, then select that method name using the class-hierarchy
browser, and then click right > Senders or
right > Implementers.