pthreads and gtk 1.2

[WPD mestrole <mestrole easynet fr>]

Hie

I want to grab stdout and stderr to display it in a GtkText.
I want to be able to do it even if the gtk_main loop is deactivated
(so I think I can't use gtk_timout_add to do it)

a piece of my code :

GtkWidget * text;
GtkWidget * window;

void * Thr (*void)
{
char  buf_err[BUFSIZ];
char  buf_out[BUFSIZ];
char B[BUFSIZ];
int n;

setbuf(stdout,buf_out);
setbuf(stderr,buf_err);

while(1)
    {
    if (buf_out[0]!=0)
        {
        fflush(stdout);
        sprintf(B,"%s",buf_out);
        n=0;
        while(B[n]!=0){
gtk_text_insert(GTK_TEXT(text),NULL,NULL,NULL,B+n++,1);}
        }
        if (buf_err[0]!=0)
        {
        fflush(stderr);
        sprintf(B,"%s",buf_err);
        n=0;
        while(B[n]!=0){
gtk_text_insert(GTK_TEXT(text),NULL,NULL,NULL,B+n++,1);}
        }
  usleep(10000);
   }
return NULL;
}


  int main(void)
{
pthread_t  pth;
int H;

... creation of the window and the gtktext...
gtk_widget_show(window);

pthread_create(&th,NULL,(void*)Thr,*void);

    printf(" 1st section\n");

H=gtk_timeout_add(.... // display values of some external captors

    printf(" 2nd section\n");
...
}

but it doesn't react very well: everything is blocked before displaying
the window with this code.
If I remove the setbuf(stderr,...) I can see 1st section on the terminal

and on the gtktext, but 2nd section only on the terminal... But not
everytime... and I get sometimes Xlib message : " sync failed ".
If I use this code replacing gtktext by a redirection to a logfile,
everything is correct.
(the pthread how-to says : with linux <2.1.x, Xlib use the two SIGUSR,
so can't use pthreads; but I do it with RTlinuxV2b12 base on kernel
2.2.10 that have much more free SIGUSR! don't understand...)

How could I get a stable processus, something doing what I want
everytime??
need help!!!