[Rd] Sending signals to current R process from R running under MS Windows (c.f. Esc)

[Graham Williams]

I am using RGtk2 for a simple GUI (rattle).

I start rattle from the RGui and I remain able to interact with the
RGui while rattle runs.

Under MS/Windows, when rattle has initiated some other underlying R
command the rattle GUI remains responsive (unlike under GNU/Linux
where it is not responsive until the underlying command completes).

I can interrupt the running command with a press of the Esc key in the RGui.

I want to have a button on the rattle GUI to run an R command to have
the same behavior as pressing the Esc key in the RGui. I currently
have a button in rattle as an example that will run another R command
whilst the original R command is still running.

Looking at the C source code for the RGui it looks like it is sending
a SIGBREAK signal to the R process.

Is this possible to do, somehow, from R?

Thanks,
Graham