[Kst] spectrum analysis - what is the default apodizing button?

[Laura Newburgh]

In the fourier spectrum analysis there is a apodizing function  
button, what is the "default" function it uses? Also, there is the  
option to take off the mean - I think this can't actually be  
subtracting a number off of the data (that would show up as a delta  
function @ zero freq in the fft), what is actually happening with  
this button? If this is obvious in the source code if you can point  
me there, that would be great...Thanks!
Laura