I've made a toolbar with some music-related buttons such as Play All, Play Random, Music tools menu button etc. which automatically appears when navigating into the music folders on the bottom position.
Is it possible to anchor/child the toolbar for example to the right pane (or the one which triggered the appearance of the toolbar)?
I don't think toolbars can dock into that position currently. They can go to the left or right of both file displays, but if they are above or below then they will be above or below both file displays at once, not just one or the other. (With the more common vertical layout. Horizontal is slightly different, of course.)