minor bugfixes about failing operations

pboard/pboard/controllers/api.py

 from tg.i18n import ugettext as _, lazy_ugettext as l_
 from tg import predicates as tgp
 
+from tg.i18n import ugettext as _, lazy_ugettext as l_
 
 from pboard.lib.base import BaseController
 from pboard.lib   import dbapi as pld
 
 __all__ = ['PODPublicApiController', 'PODApiController']
 
+FIXME_ERROR_CODE=-1
+
 class PODPublicApiController(BaseController):
 
     @expose()
       loApiController = pld.PODUserFilteredApiController(loCurrentUser.user_id)
       
       loNode = loApiController.getNode(node_id)
-      loApiController.moveNodeUpper(loNode)
+      if loApiController.moveNodeUpper(loNode)==FIXME_ERROR_CODE:
+        flash(_('Document #%s can\'t move upper.')%(node_id))
       redirect(lurl('/document/%s'%(node_id)))
 
     @expose()
       loApiController = pld.PODUserFilteredApiController(loCurrentUser.user_id)
       
       loNode = loApiController.getNode(node_id)
-      loApiController.moveNodeLower(loNode)
+      if loApiController.moveNodeLower(loNode)==FIXME_ERROR_CODE:
+        flash(_('Document #%s can\'t move lower.')%(node_id))
       redirect(lurl('/document/%s'%(node_id)))
 
     @expose()
       liParentId = loNode.parent_id
       if loNode.getChildNb()<=0:
         pm.DBSession.delete(loNode)
+        flash(_('Document #%s has been deleted')%(node_id))
+      else:
+        flash(_('Document #%s can\'t be deleted because it is not empty.')%(node_id), 'error')
+        redirect(lurl('/document/%s'%(node_id)))
+
       redirect(lurl('/document/%i'%(liParentId or 0)))
 
     @expose()