Why does the median z value seem wrong?

Question

I have a circle. I checked every single vertex's z value individually, and they're all 0.0:

But when I select all the vertices, the median for the z value is not 0:

Why isn't it showing as zero? This has been very frustrating for me. I kept trying to set the value on a larger mesh to 0 (using s -> z -> 0) to no avail. But it didn't work. So I cut down the mesh to just this small portion and I saw this problem still.

Here's the file in case you're interested:

https://www.dropbox.com/s/jqi3eljppr8gcvv/uneven.blend?dl=0

This brings up a side issue I've been having using blender. I do an action (like s -> z -> 0) and it brings up a little window in the bottom left: Is it still waiting for my input? What's it doing there? I can make it go away by deselecting vertices or something. Sometimes, like when I do a bevel, its purpose is obvious, and I change values in there and it affects the geometry. But most of the time it sits there and I need to do something funky to make it go away.

Thanks for any help with either problem!

Answer 1

The side issue can be gotten rid of by clicking anywhere on your screen. It's a part of Blender.

It's used to set how you want your scaling, moving, rotating, added object, etc.

For example: You add in a UV sphere but you don't want a lot of segments so you change the amount of segments it has using it.

Answer 2

There might be another vertex hidden on the underside of your object.