Hi everyone,

I noticed a potential problem in thread.c: the "thread apply" commands 
change the selected frame, I think it should not.
If you are doing
    (gdb) up
    (gdb) thread apply all print 1
    (gdb) down
then the frame selected before the up is not being restored by the down, 
we have an error message instead.

In the following patch:
1- I've added the restoring of the the selected frame in the restoring 
of the current thread. All is done in the 
make_cleanup_restore_current_thread() and 
do_restore_current_thread_cleanup() functions.
I don't know if there could be some cases where we don't want to restore 
the selected frame when having changed the current thread ? If so may be 
we can separate both restoring.
I'm also wondering about getting the selected frame in 
make_cleanup_restore_current_thread() directly without passing it as an 
argument. You're comments are welcome.

2- I  removed the print_stack_frame from the restore_current_thread() 
function, I think it's up to the caller to decide if he need to print or 
not the stack frame?
About that I think I must print the selected frame, not the current. 
What's your opinion ?

3- I saw in info_threads_command() that the selected frame was restored 
because the usage of switch_to_thread() changed it, so I used in 
info_threads_command() the same principle as above, using cleanup 
function. I also removed show_stack_frame() since it does nothing.

I need your opinion before going ahead in this patch.
-- 
Denis