Guification of console app

[metiu]

Say I have a console app that does something in three steps:
- opens a file
- transfers the file through a serial port
- does some elaborations

and I want to build a GUI around it that, for example, sets the file
name to open or starts the different steps.

I started using wxPython (actually boa-constructor) to build a frame
with everything I want.
The problem is: when the console app method is working, the GUI is
locked...

How can the console app communicate with the GUI in order to make it
tick (think of status messages, progress bars, log messages...)?
If I use threads and events, or wxYield, or EVT_IDLE, I'm tweaking the
console app so that it won't work just in console anymore.

How do you do that?

Thanks!