Just use gobject.io_add_watch to be notified when there is data to read and spare yourself the ordeal of using threads.

http://faq.pygtk.org/index.py?req=sh...=faq20.016.htp

def handle_data(source, condition):
__data = source.recv(1024)
__if len(data) > 0:
____self.entrybox.set_text(self.entrybox.get_text( ) + data)
____# or maybe just self.entrybox.props.text += data
____#print data
____return True # call me again if something happens
__else: # end of file
____return False # stop calling me

sock=BluetoothSocket(RFCOMM)
#sock.settimeout(15) # ?
sock.connect(('00:1F:00:B5:3A:45',5))
gobject.io_add_watch(sock, gobject.IO_IN, handle_data)

What happens is that your GUI program ALSO watches your socket and should something arrive, it will call "handle_data" which then reads the chunk that arrived (that is fast).
After that, your GUI program resumes. Note that threads didn't enter the picture anywhere (not in the GTK library either).