followPointer property
Anchors the bubble to the pointer instead of to the target.
The bubble follows the cursor while it moves over the target, which is what a chart, a map or a canvas wants: the thing being explained is the position, not the widget. Placement still runs, so the bubble flips sides near a screen edge rather than sliding off it.
Mouse only — a finger is already covering the thing the bubble explains — so pair it with HintTrigger.hover. With no pointer to follow, e.g. a hint opened from a controller, it anchors on the target as usual.
Not compatible with layer-level target tracking: a bubble that follows the cursor is positioned in overlay coordinates every move, so it does not also follow a scroll on the compositor.
Implementation
final bool followPointer;