Popup position - Popup is not always opened in the center, why not?

I get questions from users on the positioning of the popups. Popups are not always opened in the same position. Why not? How is the position being determined for a popup? Is there a relation with other opened popups?
1 answers

There is an initial position for non-modal popups which is always the same.

If you open multiple non-modal popups they will each be positioned the same distance down and to the right from the previous popup creating a cascade.

The reason for the popup cascade is that otherwise there would be no visual indication of multiple popups being open without the user actively moving or closing the top-level popup.

Once you have moved (or closed) a popup the system no longer uses that popup for reference and the position it started in is now an 'empty slot' where a new popup can be positioned.

The last popup to be opened will always be placed on top.