Ubuntu 15.04 radeon HD 4670 dual monitor open source driver works, except with trading software

I am a Linux / Ubuntu newbie.

I made a fresh install of 15.04, went flawlessly. Initially installed with one monitor, using m/b onboard VGA graphics driver. worked well, and worked well with the trading software (TDAmeritrade) That software was installed, using a *.sh script.

Then, I set up for the ATI HD4670 radeon dual monitor graphic card. The bootup was done well, and Ubuntu correctly identified and displayed on both monitors. I was using the opensource driver that came with 15.04.

All worked well, until I tried to use TDAmeritrade program. The TDAmeritrade program would initialize, and give indications that it was working. It would show the "thinkorswim' name in the title bar. But, there was no display on the screen.

I then installed JAVA jre7, per advice from another ubuntu user. No change. I have followed 'Howto...' in the ubuntu site for specific steps to verify my graphic card. The steps recommended, helped me to properly identify the card as the open source model/version RV730. So, I have had partial success....but I am missing something.

I am not ready to install WINE and use the Windows version. I would like to understand what I am missing, or where I can go to learn more about possible fixes. I am using this as part of my learning about the Linux world and Ubuntu in particular.
Any help / ideas / online sites would be appreciated.