Frozen script editor window while R console is computing

R for MAC experts:

When using the current version of R for MAC, I notice a troublesome  
behavior.  Sometimes I need to build complex regression models  
(usually using lmer) or simulations that take 10 minutes or more for  
the computer to compute.  While this computing is going on, I would  
like to be able to take advantage of this "free time" to write more  
code.  But I can't! In my current setup of R for MACs the script  
editor is frozen while the console is computing. That means that my  
only recourse is to go for a 10 minute coffee or to the toilet.  I  
don't believe that my windows version of R has this same problem.

My question:  Is there a way to set R for MAC up so that the script  
editor window is functional while the console window in chomping  
away at some calculations?

The current GUI is running in the same event loop as R in order to  
allow R to use UI elements directly. This implies that if some C code  
in R hogs the CPU without allowing UI events to be processed, it will  
block the whole UI including the editor. "Good" packages won't do that  
since R provides R_CheckUserInterrupt() call to prevent this from  
happening, but apparently some still do.

Although there is a draft of a GUI that runs R on a separate thread  
from the GUI, but it opens up a whole can of worms since all access to  
system libraries needs to be scheduled on the main thread. Since R has  
no provision for that, it would make it likely that packages will  
violate this rule thus making R unstable, especially since it's OS- 
specific. Unfortunately UIs on OS X have to run on the main thread, so  
we cannot run R on the main thread and the GUI on a separate thread.  
Therefore the best we can currently do is to rely on packages to check  
events during long computations in C code. Note that this is not an  
issue in pure R code because R makes sure the check are done.

Cheers,
Simon