Running multiple functions with Python 1.5

[Musicmaker1118]

I am trying to make a simple windowing system in python 1.5 that can run using
minimal memory. I would like for it to be able to display icons, and to be able
to run programs assosciated with them when you click on them. I would also like
it to be able to run simple programs inside of a window. To do this this, I
need to be able to run programs and monitor the movements of the mouse to
display the cursor. I plan on using a C extension for the graphics and
monitoring the mouse. The functions it defines will be run by the python code.
But I am not sure if Python 1.5 can be running different functions at the same
time, and if it is possible, how to do it. Does anyone know how this could be
done? If so, I would like to know.