closing the last open sketch quits processing.

this is different from how other applications behave on os-x. normally i would close a window
(document) before i open a new one. since the change to 126 i start to quit-restart processing
all the time.

this is a problem with java, that a window must be open for the application
to continue running.

the best we could do is to open an untitled window after you've closed the
last. this is what firefox does, for instance, but personally that drives
me nuts.

adding casey to the report to see what he thinks.

hmm .. i vote for opening a blank sketch. would be better than watching processing start-close-
start-close all the time.

my biggest problem is that i'm used to first close the frontmost doc, then open a new one.

another thing that's annoying with it: when you start processing and it opens a blank sketch
and you close that to open one of your projects it actually quits again.

that's just a matter of getting used to the new model. don't close before
opening a new sketch, and your sketch will replace the untitled sketch.

k, i've come to a resolution on this one. there's a preference that ensures
that an untitled window stays open. on windows/linux this is turned off by
default. on the mac it's turned on. users can go with either model by
checking the box. this is implemented for 0131.