VisibilityDetector reports widget as visible even when covered by a fullscreen dialog

[nikkieke]

Problem description

I’m using the visibility_detector package to track when a widget is visible to the user. However, I’ve noticed that if the widget is covered by a fullscreen dialog, the detector still reports it as visible.

This causes incorrect behavior in scenarios where I want to pause/resume activity depending on whether the widget is truly visible to the user.

Steps to reproduce

1. Place a VisibilityDetector around any widget.
2. Trigger a fullscreen Dialog (e.g., showDialog with barrierDismissible: true and full-screen child).
3. Observe that VisibilityDetector still reports visibleFraction = 1.0.

Expected behavior

The VisibilityDetector should detect that the widget is no longer visible to the user when it’s covered by a fullscreen dialog.

Actual behavior

The VisibilityDetector continues to report visibleFraction = 1.0, even though the widget is completely covered.

Environment

Flutter version: 3.29.0

visibility_detector: 0.4.0+2

Platform: Android & iOS