fixed the problem with generating several roots in ud2gf. Now only the leftmost word becomes ROOT, the others become dep - which can be eliminated by cnclabels. This works fine for e.g. English prepositional and particle verbs. But it does not work if the 'main' word is not the leftmost one

src/runtime/haskell/PGF/VisualizeTree.hs

@@ -144,7 +144,7 @@ graphvizDependencyTree format debug mlab mclab pgf lang t =
                             vcat links) $$
                     text "}"
   where
-    conll  = maybe conll0 (\ls -> fixCoNLL ls conll0) mclab
+    conll  = fixCoNLL (maybe [] id mclab) conll0
     conll0 = (map.map) render wnodes
     nodes  = map mkNode leaves
     links  = map mkLink [(fid, fromMaybe (dep_lbl,nil) (lookup fid deps)) | ((cat,fid,fun,_),_,w) <- tail leaves]
@@ -771,12 +771,23 @@ type CncLabels = [
   ]
 
 fixCoNLL :: CncLabels -> CoNLL -> CoNLL
-fixCoNLL cncLabels conll = map fixc conll where
+fixCoNLL cncLabels conll = map fixc (markRoot conll) where
   labels  = [l | Left l <- cncLabels]
   flabels = [r | Right r <- cncLabels]
 
+-- change the root label from dep to root
+--- doing this for the leftmost word of the root node
+  markRoot rows = case rows of
+    (i:word:fun:pos:cat:x_:"0":"dep":xs):rs -> (i:word:fun:pos:cat:x_:"0":"root":xs) : map (markNoRoot i) rs
+    r:rs -> r : markRoot rs
+    _ -> rows --- what about if there is no root?
+
+  markNoRoot r row@(i:word:fun:pos:cat:x_:j:label:xs) = case j of
+    "0" -> (i:word:fun:pos:cat:x_: r :label:xs)
+    _ -> row
+    
   fixc row = case row of
-    (i:word:fun:pos:cat:x_:"0":"dep":xs) -> (i:word:fun:pos:cat:(feat cat word x_):"0":"root":xs) --- change the root label from dep to root 
+ 
     (i:word:fun:pos:cat:x_:j:label:xs) -> case look (fun,word) of
       Just (pos',label',"head") -> (i:word:fun:pos' pos:cat:(feat cat word x_):j :label':xs)
       Just (pos',label',target) -> (i:word:fun:pos' pos:cat:(feat cat word x_): getDep j target:label':xs)