Switch focus on G3000/5000 with GTC in VR with mouse

Hi,

Maybe something I’m overlooking, but how can I switch the focus on the G3000/G5000 with the GTC? I know it’s by moving the leftmost button on the GTC to the left and right, but it doesn’t work in VR with the mouse.

Can anyone guide me on how to do this?

Thanks

E.