That means the element has absolute position within a parent element with auto layout.

That clarifies, thank you.

Sometimes I also get a box around the alignment options when I hold shift



.

I can’t reproduce it right now. Do you also know what that is supposed to do?

That’s something different. It takes the elements you have in selection and it works with them as it was a group. This is useful, e.g. if you want to align the selection to the parent element and not relative to the selected elements.

Oh I see, thanks a lot @Marian_Brchan !