Setbuffer..........

I think you are right. I tried it and it seems to reset the viewport after each SetBuffer()

Graphics 800, 600, 0, 2
SetBuffer BackBuffer()

Viewport 0, 0, 400, 300
ClsColor 0, 255, 0
Cls

im = CreateImage(400, 300)
SetBuffer ImageBuffer(im)
SetBuffer BackBuffer()

Viewport 0, 0, 400, 300
Cls
For i = 0 To 1000
Text 0, i * 20, "orituierutooreiuwtoiureiouoituroiewuoituoirewuigthdjkfshglkjhfdskhjgkhfdsjkhgkjhfdksjhgkjfdjskhg"
Next

Flip

WaitKey()
End