Bug 312540 [LinkedResources] Copy resource in Navigator and Project Explorer always shows dialog
N20100511-2000. When copying an IFile from one to another folder in the Navigator or Project Explorer, I always get the dialog no matter how I've set the preferences on the 'Linked Resources' page (even if I disable linked resources).
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/views/navigator/NavigatorDropAdapter.java
/**
     * Ensures that the drop target meets certain criteria
     */
    private IStatus validateTarget(Object target, TransferData transferType) {
        if (!(target instanceof IResource)) {
            return info(ResourceNavigatorMessages.DropAdapter_targetMustBeResource);
        }
        IResource resource = (IResource) target;
        if (!resource.isAccessible()) {
            return error(ResourceNavigatorMessages.DropAdapter_canNotDropIntoClosedProject);
        }
        IContainer destination = getActualTarget(resource);
        if (destination.getType() == IResource.ROOT) {
            return error(ResourceNavigatorMessages.DropAdapter_resourcesCanNotBeSiblings);
        }
        String message = null;
        
        if (LocalSelectionTransfer.getInstance().isSupportedType(transferType)) {
            IResource[] selectedResources = getSelectedResources();
            if (selectedResources.length == 0) {
				message = ResourceNavigatorMessages.DropAdapter_dropOperationErrorOther;
			} else {
                CopyFilesAndFoldersOperation operation;
                if (lastValidOperation == DND.DROP_COPY) {
                    operation = new CopyFilesAndFoldersOperation(getShell());
					if (operation.validateDestination(destination, selectedResources) != null) {
						operation.setVirtualFolders(true);
						message = operation.validateDestination(destination, selectedResources);
					}
                } else {