In the upper left corner below the weapon bar, there's nothing rendered, yet, i can click there to select a slave of mine. With further testing i found out that it's the same thing as the clickable slave icons in the upper right corner, a bit more up, except that clickables on the left arent shown.

The top bar's window doesn't stop the rendering beneath it, nor does it block clicks from passing through!

No i dont meant the top bar, just a little below it. Now i also got another theory, it doesnt work when slaves are close, and it also works on any other objects that can have a floaty. So what i think is that when i'm all the way zoomed out the floaties are still there, just not shown.