Hi Jon,
just FYI: the 'apple' way of doing this would likely involve a popover rather than a popup.
This can accommodate larger/multiple interface elements.. See the apple HIG on this here: https://developer.apple.com/design/huma ... /popovers/
Or if there is a huge number of controls/information to be displayed then a panel, which would be equivalent to a substack.
Sadly LC does not provide a popover widget or similar - I simulate this with a group - using a substack would be a bit more difficult due to the positioning of the arrow, which will have to vary if the interface element it points to is near an edge of the stack/screen (ie the arrow would be in the same physical location but the 'bubble' of the popover would have to shift relative to this to always be visible -- easier to do with a group). I've created a reusable group for my projects which i'll share at some point -- but a 'panel' may suit your needs more? Have a look at the links...