Or instead of more context menu entries, how 'bout a modifier key while opening? Default: enque and play. modifier held down: open selected files separately and play simultaneously.
I think for normal usage, the current behaviour is fine. How often do you want to play back files simultaneously with a media player? For demoing, double-clicking one file after another is even better.
I do agree, there should be a mechanism to have dropped files be appended to the running play list. I’d suggest a right-drag’n’drop context menu as Tracker does with files.
If I remember correctly, SoundPlay had a tracker-addon named “enqueue in SoundPlay” that automatically add the files to the current playlist.
Both of them actually works in Haiku.
A smart and simple solution could be that when multiple files are dragged, a pop-up is given to the user. When files are opened instead, they are added to the playlist.
I don’t see a reason to make things so complex for a so simple thing, sincerely.
Select your files right click on the selection choose open with -> MediaPlayer
It will play them one after the other.