How to save browser path in the dialog

[Al]

I created a dialog, and there are three file browsers for finding the file. Since there are all in the same folder, it is no necessary to going through all path after finding the first file. The second and third files shall automatically getting the same path from the first. My questions are how to save the path of first file and show the path in the editbox of the second and third files ?

Anyone can give me some help, and I will highly appreciated.