$thread convenience variable

[Vladimir Prus]

Hello!

Is there some convenience variable that holds the number of the current
thread, or alternatively, the thread where breakpoint was hit. Such a
variable would allow me to write
 
   breakpoint foo.cpp:10 if $thread==1 || $thread==2

If I understand correctly, at the moment gdb can't specify arbitrary
condition on thread number for breakpoint. A breakpoint is either global,
or for one thread.

If such variable does not exist, does it look like a good addition?

- Volodya