Set default spectator window positon and window size

hardware:
using 3 1080p TV to setup horizontal 3screens and the windows properties shown in the photo

total screen resolution is 5760x1080

I setup two child windows and display 2d widget by using SWindow class and it works well.
But problem happens that neither r.setres nor GetActiveWindow() then MoveWindow() work for the default VR spectator window(not the vr spectator screen come up with 4.17, just default VR spectator window),but they works when disable HMD.

It seems that the default VR spectator window has same resolution of one eye in HMD, it can recive r.setres console but nothing happen.

Can anyone tells me how to modify the resolution of the default spectator window and set the location of it?
thx a lot!

r.setres 1920x1080f works,but it with bring glitch problem to the window