MUI design

Hi all, I am working on a 3D viewer application and need more 2 GUI windows for setting input parameters. I have created first GUI window under the mui library. But the second one still does not work well. The widgets which I created on the first GUI window is copied to the second GUI window automatically even though I created different UI list by muiNewUIList and muiSetActiveUIList. I drew other different widgets on the second window but they are not available. What will happen on MUI when the multiple GUI window created by this library?

Other question: is there any easy way to create a file browser by MUI?

Thank you in advance for any help and answers!