That's a design choice. Visualising a terabyte-size volume requires a great hardware effort especially by the graphic card. Allowing multiple volume visualization would likely make the effort not easily manageable or even not feasible.

So no, we do not plan to change this.

However, as Hanchuan said, you can open multiple instances of Vaa3D. But I do not guarantee that it will work smoothly, for the same reasons mentioned above.

Originally posted by marionac: