"Open File" dialog with glut

Hi everyone!

I’m developing a program that renders volume data with glut and GLUI.
I need to open file in order to read some kind of data and now I’m using a sad static GLUI dialog with a radiogroup where the user can choose what file to open, but the program doesn’t know if that files really exists or not, and doesn’t know if there are other file of the kind he needs.

Anyone of you developed something like an open file dialog that read the file with a specific extension from the file system, and allow to choose one?
Something like the one you can use with VC++! But I want
ONLY platform independent programs! Opengl forever!

I don’t know how to read files from the file system, and I’m very sad about this…

Please, help me!

I think in fcntrl.h there are command to scan the dirs and a stat command that returns the info on a file if it exists
im not sure on the exact header it been along time.