Inactive controls

[AINER]

Description of the new feature / enhancement

Remove duration bar for content with invaluable duration data and inactive next / previous buttons.

Scenario when this would be used?

This will make the interface lighter and solve attempts to use inactive controls.

Additional context

The inactive button has a stronger color accent than the active button, which can cause false clicks from users. To solve the problem, you can either remove the background of the button, then it will be more faded than the next track button, or remove it entirely.

[manstheram]

Should be pretty easy to add.

[AINER]

Add some information about other UI elements.

[manstheram]

It turns out the duration bar hides itself automatically in the beta, so that part's already done.

[manstheram]

I removed the background from the button in my pull-request 👍 @AINER