flowgraph reading keystrokes during execution

Dear Sir,

I am thinking of building simple chat application using gnuradio.
PC#1 connecting to USRP#1, will send text message to PC#2 via USRP#2.
The question is, how to get the user keystrokes from the flowgraph at PC#1 ?

I am building the flowgraphs using GRC (Companion).
I guess I need to use something similar to WX GUI Slider, that get the
user keystrokes instead of the slider position, into the flowgraph,
during its execution.

Thanks in advance.