Edward,
It does appear that the Adjust View GUI needs to be open for the view parameters to be adjusted and updated correctly. This is because the Parms reside in the screen class, which only exists when the screen is open. For what you're trying to work we'll likely need to move the Parms and parts of the Update function out of the GUI class so they can be available to non-GUI classes like the Vehicle Parm Container.
Calling "vsp -script" from the command line without the GUI currently won't let the adjust view Parms even be set. However, ScreenGrab will work regardless of if the GUI s open or not. When it won't work is when OpenVSP is compiled without the GUI at all.
I think it would be good to relocate the Adjust View parms so you can use them from the API without the GUI even being open. Rob, if you have any thoughts on this please let me know.
Overall I don't think this change will be significantly difficult to support, so I'll make an effort to do so before the next release.
Thanks,
Justin