I do think you need to make a very small modification to the OI. The source files for the NI OIs are in:
<Program Files>\National Instruments\TestStand 3.5\OperatorInterfaces\NI\Full-Featured\
There are separate folders for C++ using MFC, CSharp, VB.Net, and LabVIEW. Open the folder that corresponds to the development environment you prefer. Then open the .sln, .prj, or .llb. In each project will be a form, panel, or VI that contains an ApplicationMgr activeX control that is only visible at design time. Edit the ActiveX properties for this control to change this setting or set the property from the source code before the point where ApplicatonMgr.Start is called.
If you still need guidance, please specify which development environment you want to use.
- James