Index button on smaller screens

If there is no space the index is hidden by default.

In this case, a dynamic bar shows up at the bottom with an index button. Like here.

The above only happens if there is 1 replies or more. Most of my docs have zero replies, like here - in this case the same index button does not show up.

Not sure if this is a bug, or should be a feature

Discuss this on our forum.