Qt.Popup flag is unreliable on macOS inside QDialog parents — popup may
appear behind the parent or not receive clicks. Replace with a small
QDialog using Qt.Tool|Qt.FramelessWindowHint which is stable on macOS.
- Add explicit close button (✕) in the popup
- Call activateWindow() to ensure popup gets focus
- Position 4px below the help button for visual separation
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>