[racket] text-field% locking

See

 http://docs.racket-lang.org/gui/editor-overview.html#%28part._editorthreads%29

The short answer is that editors aren't thread-safe in any simple
sense. That section of the docs provides some information on working
with multiple threads, but please ask again if I've misunderstood or if
the docs don't provide enough help.

At Sun, 5 Jun 2011 20:08:34 +0200 (CEST), Ivanyi Peter wrote:
> Dear All,
> 
> I have a problem.
> I try to execute a command line program from my Scheme program.
> The stdout and stderr of the command line program should 
> be redirected to a text-field%. I have one program which
> writes to stdout and stderr quite quickly and I get the
> following error:
> 
> iproc.scm:79:24: sequence-contract-violation: negative: method insert cannot be 
> called, except in states (unlocked), args "iProc ERROR:  Run Time:     0.00 
> seconds\r"
> 
> It seems, there is some problem with locking.
> I also include the iproc.scm file, which executes the external
> command line program.
> What can I do to solve this problem???