Whenever I try to drag and drop a file to an existing VLC player ( as per Drag & Drop Files and Items in Unity ! ), it seems to open a new VLC window and start playing from there. Is it possible to run it from the existing open window?
open vlc > tools > preferences. there is an Instances section, enable "Allow only one instance'
There is also an option to " Enqueue files when in one instance mode" On recent versions of vlc that actually works. Enable if desired & see if it does.
Make sur you click save on your way out of prefs