Bug 86515 [Drag and Drop] Drag and drop (move) for project
Drag and drop (move) for project onto Explorer deletes the project from the file system. But this is not reflected in the workspace. Pressing refresh - provides dialog "location deleted" and remove project from the workspace.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/packageview/FileTransferDragAdapter.java
FileTransferDragAdapter(ISelectionProvider provider) {
		fProvider= provider;
		Assert.isNotNull(fProvider);
	}
	public Transfer getTransfer() {
		return FileTransfer.getInstance();
	}
	
	public void dragStart(DragSourceEvent event) {
		event.doit= isDragable(fProvider.getSelection());
	}
	
	private boolean isDragable(ISelection s) {
		if (!(s instanceof IStructuredSelection))
			return false;
		IStructuredSelection selection= (IStructuredSelection)s;
		for (Iterator iter= selection.iterator(); iter.hasNext();) {
			Object element= iter.next();
			if (element instanceof IJavaElement) {
				IJavaElement jElement= (IJavaElement)element;
				int type= jElement.getElementType();
				
				if (type != IJavaElement.JAVA_PROJECT && type != IJavaElement. PACKAGE_FRAGMENT_ROOT &&
					type != IJavaElement.COMPILATION_UNIT && type != IJavaElement.TYPE)
					return false;
				IPackageFragmentRoot root= (IPackageFragmentRoot)jElement.getAncestor(IJavaElement.PACKAGE_FRAGMENT_ROOT);
				if (root != null && root.isArchive())
					return false;
			}
		}