Sometimes I want to use my portal in portrait mode while it's in landscape orientation - that is, if I'm lying in bed, I don't want the call to transition to landscape mode. Phones have rotation lock to allow this, and it'd be great if Portal had it too. A workaround is to flip Portal upside down, but that only enables locking the orientation if the user is to the right of the device. A rotation lock would allow it to work when the user is to the left of the device and also make it much more stable since it can rest on the stand in that orientation.