Changing items on Audio Mixer Setup switches tabs unexpectedly

[agildehaus]

In the Audio Mixer settings in Media Preferences:

1. Navigate to the Setup tab.
2. Check "Use non linear gain sliders (like BeOS R5). Alternatively, change the value in the drop down box for "Input gain controls represent".

Result:

The tab will change from Setup back to the Gain Controls. This is unexpected behavior and has no reason to occur.

[korli]

Dup of #1876