it would be great to be able to drag'n'drop to the playqueue from any other main mode views and have it visible to manage as well while in the other views.
Here's a screenshot of a sneek-preview what we are currently working on.
It allows you to dock the Play queue in the right sidebar, when docked, the Play queue button will be hidden from the player.
We hope to release this feature for early beta testing soon:
Fixed in Helium 12.0.3 (beta), https://implodedsoftware.wordpress.com/2016/09/16/helium-12-0-3-beta-now-available/
We have some rough plans to let the Play queue be embedded in the right-sidebar, but further testing is needed before we can say if and when this can be done.