Change dialog size an location of filechooser

I have an application I wrote that currently works well on windows and andriod. I am now trying to build this for a raspberry pi. I can build it and it runs fine. But I am using a small lcd screen (320x480). When I use the filebrowser class for file selection, the dialog is too big and centers such that the upper left corner is way off the screen. Basically the screen just goes white with no way to select anything.

I an trying to figure out how to change the size of the dialog created. I assume the filechooserdialogbox is used but the default is too big, and is centered. How do I control the size of the dialog presented?

Here is the code for Linux:
FileChooser chooser(“Select a Set to load…”,
if (chooser.browseForFileToOpen())
File file(chooser.getResult());
SetDir = file.getParentDirectory();
dirty = false;
SetName = file;

I changed it to use fileChooseDialogBox and that works because I can do showAt and specify location and size. The only draw back is I can only select on file at a time.