Virtual Buffer Support Functions

The fg_vbundef() function releases a virtual buffer handle but does not release the virtual buffer memory. It is designed for virtual buffers created with fg_vbdefine(), as fg_vbfree() frees the virtual buffer memory and the virtual buffer handle. Its only parameter is the virtual buffer handle to release.

The fg_vbhandle() function returns the active virtual buffer handle, or -1 if no virtual buffer is active. It has no parameters.