Problem with Web Start on Linux

Hi Friends,
I have a problem with Java Web Start.
At start up of our swing application has Login dialog Box.
This application is started with jnlp file.
On windows our application is working properly.
But on Linux, when application started through jnlp file, all dialog box not showing properly. Its size contracts. Same problem with all dialog box in our application.
I m not getting, is it problem with WebStart or JRE version or something related to linux..
Does anyone have any solution for this?

Thanx in advance
Abhishek