Decibel Flyouts are broken

### Bug description

If the User opens any slider that contains a decibel flyout, for example:
- Microphone Level Slider
- Graphic EQ Slider
- Gain Slider on Tracks
- Volume Level Slider
After dragging the slider the flyout will become stuck and be shown when it should not be.

### Steps to reproduce

1. Launch AU4
2. Use any slider that contains a decibel flyout
3. Observe result

### Expected behavior

The decibel flyout should be hidden once the slider is not in use or focus.

### Actual behavior

The decibel flyout is not hidden once the slider is not in use or focus.

### Audacity Version

9f85aba0843986f8e23415483e1d4b000c290e6c

### Operating system

OS independent

### Additional context