Overlapping controls in metadata editor gallery detail view for multimedia files

[solth]

Describe the bug
The controls for audio or video tracks overlap with the buttons to navigate to the first/previous/next/last media of a process, that fade in on mouse hover in the gallery detail view of the metadata editor.

To Reproduce
Steps to reproduce the behavior:

1. Open a process with an audio or video file in the metadata editor
2. Select the audio/video file and switch to the detail view
3. Hover with the mouse over the detail view
4. See overlapping controls

Expected behavior
The individual controls shouldn't overlap each other and their layout should be refactored accordingly.

Screenshots

Release
3.8, 3.9-snapshot

[solth]

Update: this overlapping only occurs when the waveform visualization of audio files is enabled in the project settings. Without the waveform the controls to not overlap: