Hello!
Well this is the problem: I have a Ge Force 8400GS Card, with a DVI and VGA output. Currently i’m using the vga output, but I was wondering if I could use the other connector with other monitor. How can I handle the contexts to work with both displays. I would like a solution that works with any GPU vendor(NVIDIA, AMD, Intel). OS dependant calls mare aceptable. Help please 
Use the “Configuring Multiple X Screens on One Card” approach, described in Chapter 15 of the NVidia driver README.
Alternatively use Xinerama (Chapter 14) or TwinView (Chapter 13).
Which is best depends on your application.