Playlist move on drag instead of copy on drag

Hi guys, 

If I drag a playlist entry from any other playlist than "Collection" to playlist, the playlist entry should be moved and not copied. Copying already can be done by right clicking and use the add to playlist option.

When I drag from collection to any other playlist it should be copied.

If this feature request is too difficult because it touches core playlist functionality please add the feature with a shortcut like <Ctrl> - Drag.