[Popup] Misaligned positioning when parent has scrollbar

[lubber-de]

Description

Popups which are right positioned are misaligned by the width of a possible scrollbar (or any margin of the parent element (usually body))

Testcase

The body has a scrollbar. Open the modal by clicking the button and hover over the icon to see the popup.

Broken

The popup arrow is misaligned to the right by the width of the body scrollbar https://jsfiddle.net/dutrieux/npjsc5d8/

Fixed

Arrow positioned correctly again https://jsfiddle.net/lubber/zh5xypob/

Screenshot

Broken

Fixed

Closes

#1899

[dutrieux]

The behavior is not the same with pre-formatted popup : https://jsfiddle.net/dutrieux/npgdc2mw/