To position an overlay (tooltip, popover) near a trigger element, you need the trigger's exact position on screen, including scroll offsets.
The native getBoundingClientRect() alone is not enough because you also need viewport
dimensions.
Gets the bounding rectangle of an element relative to the viewport. Also returns viewport width/height and scroll offsets. Handles nested scrollable containers.
OverlayPositioner, Tooltip, Popover, Dropdown, ContextMenu, Select