src/vs/base/browser/ui/splitview/paneview.ts/PaneDraggable/constructor
class PaneDraggable:	constructor(private pane: Pane, private dnd: IPaneDndController, private context: IDndContext) {
		super();

		pane.draggableElement.draggable = true;
		this._register(addDisposableListener(pane.draggableElement, 'dragstart', e => this.onDragStart(e)));
		this._register(addDisposableListener(pane.dropTargetElement, 'dragenter', e => this.onDragEnter(e)));
		this._register(addDisposableListener(pane.dropTargetElement, 'dragleave', e => this.onDragLeave(e)));
		this._register(addDisposableListener(pane.dropTargetElement, 'dragend', e => this.onDragEnd(e)));
		this._register(addDisposableListener(pane.dropTargetElement, 'drop', e => this.onDrop(e)));
	}