How come individual applications can't be put on a virtual desktop in winecfg?

[Scott Ritchie]

I have a single, very old application that needs to run in Windows 98
mode with a 640x480 virtual desktop.

But, I'd like to run other applications at the same time.  How come I
can't set winecfg to make a virtual desktop for just this application,
and handle everything else in the window manager?

Thanks,
Scott Ritchie