Corner is a simple 'hot-corners' implementation. It instantiates a
CornerDelegate object and sends it messages of the form -enterTopLeft and
-exitTopLeftAfter: for each corner, where the exit message takes the number of
seconds the mouse spent in that corner as an argument.
The delegate simply ignores these messages by default. A category on this
object, however, can be provided. If you store a Smalltalk script in the
"CornerScript" default as a string object then this will be loaded
automatically and compiled. If this contains a category on CornerDelegate then
the Smalltalk implementation will be called instead. A trivial example might
log a message when the corner was entered was called:
$ defaults write Corner CornerScript \
"CornerDelegate extend [ enterTopLeft [ 'Script called' log. ] ]"