A long time ago, I tried to improve the interactiveness
of DrRacket when the contour window was open with the
code that is removed in this commit. Looking at it today,
it seems clear that this code was buggy (and, now that
we've had lots of experience with it, it didn't actually
help with interactivity either)
The problem is that the code didn't record enough
information about the change to the editor in the thunk put
into the 'todo' field. It would remember that a particular
range was out of date, but it woudln't remember which
characters were in that range, so when it would go to copy
the characters, it may be getting the wrong characters
(since another edit may have happened since the thunk was
stored in the todo field)
This change also has the side benefit that the time it takes
to change the contour window is now being tracked by the
colorer, which means that it'll give up a bit sooner
coloring less in each go, but hopefully maintaining the
interactivity
original commit: 052ee14afc748929f9195620c183f053d307ac21
8311497772