diff --git a/gap/dot.gi b/gap/dot.gi
index 2dfa745..f53b0ba 100644
--- a/gap/dot.gi
+++ b/gap/dot.gi
@@ -50,6 +50,8 @@ function(arg...)
       [msg]);
 end);
 
+DeclareOperation("GV_GraphSearchChildren", [IsGVGraph, IsFunction]);
+DeclareOperation("GV_GraphTreeSearch", [IsGVGraph, IsFunction]);
 DeclareOperation("GV_GetCounter", [IsGVGraph]);
 DeclareOperation("GV_IncCounter", [IsGVGraph]);
 DeclareCategory("IsGV_Map", IsObject);
@@ -549,9 +551,14 @@ function(g)
   local result, edges, nodes, kind;
 
   result := "";
-  edges  := Length(GraphvizEdges(g));
-  nodes  :=
-            Length(GV_MapNames(GraphvizNodes(g)));
+  edges  := 0;
+  nodes  := 0;
+
+  GV_GraphSearchChildren(g, function(s)
+    nodes := nodes + Length(GV_MapNames(GraphvizNodes(s)));
+    edges := edges + Length(GraphvizEdges(s));
+    return false;
+  end);
 
   if IsGVDigraph(g) then
     kind := "digraph";
@@ -724,7 +731,36 @@ InstallMethod(GV_GetParent,
 "for a graphviz graph",
 [IsGVGraph], graph -> graph!.Parent);
 
-DeclareOperation("GV_GraphTreeSearch", [IsGVGraph, IsFunction]);
+# tree search only on the children of the graph
+InstallMethod(GV_GraphSearchChildren,
+"for a graphviz graph and a predicate",
+[IsGVGraph, IsFunction],
+function(graph, pred)
+  local _, curr, queue, count, subs, key;
+
+  queue := [graph];
+  while Length(queue) > 0 do
+    count := Length(queue);
+
+    for _ in [1 .. count] do
+      # TODO: make sure this is using a linked list rather than an array list
+      curr := Remove(queue, 1);
+
+      # Check this graph (visit)
+      if pred(curr) then
+        return curr;
+      fi;
+
+      # Add children
+      subs := GraphvizSubgraphs(curr);
+      for key in GV_MapNames(subs) do
+        Add(queue, subs[key]);
+      od;
+    od;
+  od;
+
+  return fail;
+end);
 
 InstallMethod(GV_GraphTreeSearch,
 "for a graphviz graph and a predicate",
@@ -1189,9 +1225,38 @@ end);
 InstallMethod(GraphvizRemoveAttr, "for a graphviz graph and an object",
 [IsGVGraph, IsObject],
 function(obj, attr)
-  local attrs;
-  attrs      := GraphvizAttrs(obj);
-  obj!.Attrs := Filtered(attrs, item -> item[1] <> String(attr));
+  local attrs, i, k, str, match;
+
+  attrs := GraphvizAttrs(obj);
+  attr  := String(attr);
+
+  # remove by value
+  if '=' in attr then
+    obj!.Attrs := Filtered(attrs, item -> item <> attr);
+  else
+
+    for k in [1 .. Length(attrs)] do
+      str := attrs[k];
+
+      # check if the string is of the form '`attr`=...'
+      match := true;
+      for i in [1 .. Length(attr)] do
+        if i > Length(str) or attr[i] <> str[i] then
+          match := false;
+          break;
+        fi;
+      od;
+      match := match and i + 1 <= Length(str) and str[i + 1] = '=';
+
+      # if so remove it
+      if match then
+        RemoveElmList(attrs, k);
+      else
+        k := k + 1;
+      fi;
+    od;
+
+  fi;
   return obj;
 end);
 
diff --git a/tst/examples/er.tst b/tst/examples/er.tst
index a1dcbf3..8f0d58d 100644
--- a/tst/examples/er.tst
+++ b/tst/examples/er.tst
@@ -99,9 +99,9 @@ gap> GraphvizSetAttrs(GraphvizAddEdge(e, "course", "S-C"),
 
 #
 gap> GraphvizSetAttr(e, "label=\"Entity Relation Diagram\ndrawn by NEATO\"");
-<graphviz graph ER with 0 nodes and 12 edges>
+<graphviz graph ER with 12 nodes and 12 edges>
 gap> GraphvizSetAttr(e, "fontsize=\"20\"");
-<graphviz graph ER with 0 nodes and 12 edges>
+<graphviz graph ER with 12 nodes and 12 edges>
 
 #
 gap> AsString(e);
diff --git a/tst/examples/traffic_lights.tst b/tst/examples/traffic_lights.tst
index 295ac0f..5fc2359 100644
--- a/tst/examples/traffic_lights.tst
+++ b/tst/examples/traffic_lights.tst
@@ -69,14 +69,14 @@ gap> for pair in [[2, 1], [1, 2]] do
 
 #
 gap> GraphvizSetAttr(t, "overlap=\"false\"");
-<graphviz digraph TrafficLights with 0 nodes and 16 edges>
+<graphviz digraph TrafficLights with 14 nodes and 16 edges>
 gap> GraphvizSetAttr(t,
 > """label="PetriNet Model TrafficLights
 > Extracted from ConceptBase and laid out by Graphviz"
 > """);
-<graphviz digraph TrafficLights with 0 nodes and 16 edges>
+<graphviz digraph TrafficLights with 14 nodes and 16 edges>
 gap> GraphvizSetAttr(t, "fontsize=12");
-<graphviz digraph TrafficLights with 0 nodes and 16 edges>
+<graphviz digraph TrafficLights with 14 nodes and 16 edges>
 
 #
 gap> AsString(t);
diff --git a/tst/graph.tst b/tst/graph.tst
index a0aea1d..ed5428c 100644
--- a/tst/graph.tst
+++ b/tst/graph.tst
@@ -241,5 +241,41 @@ gap> GraphvizSetColor(g, "red");;
 gap> GraphvizAttrs(g);
 [ "color=red" ]
 
+# testing removing attributes from graphs by value
+gap> g := GraphvizGraph();;
+gap> GraphvizSetAttr(g, "label", "test");;
+gap> GraphvizAttrs(g);
+[ "label=test" ]
+gap> GraphvizSetAttr(g, 1, 2);
+#I  unknown attribute "1", the graphviz object may no longer be valid, it can be removed using GraphvizRemoveAttr
+<graphviz graph with 0 nodes and 0 edges>
+gap> GraphvizAttrs(g);
+[ "label=test", "1=2" ]
+gap> GraphvizRemoveAttr(g, "1=2");
+<graphviz graph with 0 nodes and 0 edges>
+gap> GraphvizAttrs(g);
+[ "label=test" ]
+
+# testing removing attributes from graphs by key
+gap> g := GraphvizGraph();;
+gap> GraphvizSetAttr(g, "label", "test");;
+gap> GraphvizAttrs(g);
+[ "label=test" ]
+gap> GraphvizSetAttr(g, 1, 2);;
+#I  unknown attribute "1", the graphviz object may no longer be valid, it can be removed using GraphvizRemoveAttr
+gap> GraphvizAttrs(g);
+[ "label=test", "1=2" ]
+gap> GraphvizRemoveAttr(g, 1);;
+gap> GraphvizAttrs(g);
+[ "label=test" ]
+gap> GraphvizRemoveAttr(g, "label");;
+gap> GraphvizAttrs(g);
+[  ]
+gap> GraphvizSetAttr(g, 1, 2);;
+#I  unknown attribute "1", the graphviz object may no longer be valid, it can be removed using GraphvizRemoveAttr
+gap> GraphvizRemoveAttr(g, "label");;
+gap> GraphvizAttrs(g);
+[ "1=2" ]
+
 #
 gap> STOP_TEST("graphviz package: graph.tst", 0);
diff --git a/tst/node.tst b/tst/node.tst
index 6388f06..9396a8d 100644
--- a/tst/node.tst
+++ b/tst/node.tst
@@ -112,5 +112,64 @@ gap> s := GraphvizGraph();;
 gap> GraphvizAddNode(s, n);
 Error, Cannot add node objects directly to graphs. Please use the node's name.
 
+# Test updating an attribute
+gap> g := GraphvizGraph();;
+gap> n := GraphvizAddNode(g, "n");;
+gap> GraphvizSetAttr(n, "label", "a");;
+gap> AsString(g);
+"//dot\ngraph  {\n\tn [label=a]\n}\n"
+gap> GraphvizSetAttr(n, "label", "b");;
+gap> AsString(g);
+"//dot\ngraph  {\n\tn [label=b]\n}\n"
+gap> GraphvizSetAttr(n, "color", "red");;
+gap> AsString(g);
+"//dot\ngraph  {\n\tn [color=red, label=b]\n}\n"
+gap> GraphvizSetAttr(n, "color", "blue");;
+gap> AsString(g);
+"//dot\ngraph  {\n\tn [color=blue, label=b]\n}\n"
+
+# test changing labels functions properly
+gap> g := GraphvizGraph("xxx");;
+gap> GraphvizAddNode(g, 1);;
+gap> GraphvizAddNode(g, 2);;
+gap> GraphvizAddNode(g, 3);;
+gap> GraphvizSetNodeLabels(g, ["i", "ii", "iii"]);
+<graphviz graph xxx with 3 nodes and 0 edges>
+gap> AsString(g);
+"//dot\ngraph xxx {\n\t1 [label=i]\n\t2 [label=ii]\n\t3 [label=iii]\n}\n"
+gap> GraphvizSetNodeLabels(g, ["a", "b", "c"]);
+<graphviz graph xxx with 3 nodes and 0 edges>
+gap> AsString(g);
+"//dot\ngraph xxx {\n\t1 [label=a]\n\t2 [label=b]\n\t3 [label=c]\n}\n"
+
+# test changing labels and colors functions properly
+gap> g := GraphvizGraph("xxx");
+<graphviz graph xxx with 0 nodes and 0 edges>
+gap> GraphvizAddNode(g, 1);
+<graphviz node 1>
+gap> GraphvizAddNode(g, 2);
+<graphviz node 2>
+gap> GraphvizAddNode(g, 3);
+<graphviz node 3>
+gap> GraphvizSetNodeColors(g, ["i", "ii", "iii"]);
+Error, invalid color "i" (list (string)), valid colors are RGB values or names\
+ from the GraphViz 2.44.1 X11 Color Scheme http://graphviz.org/doc/info/colors\
+.html
+gap> GraphvizSetNodeColors(g, ["red", "green", "blue"]);
+<graphviz graph xxx with 3 nodes and 0 edges>
+gap> AsString(g);
+"//dot\ngraph xxx {\n\t1 [color=red, style=filled]\n\t2 [color=green, style=fi\
+lled]\n\t3 [color=blue, style=filled]\n}\n"
+gap> GraphvizSetNodeColors(g, ["red", "#00FF00", "blue"]);
+<graphviz graph xxx with 3 nodes and 0 edges>
+gap> AsString(g);
+"//dot\ngraph xxx {\n\t1 [color=red, style=filled]\n\t2 [color=\"#00FF00\", st\
+yle=filled]\n\t3 [color=blue, style=filled]\n}\n"
+gap> GraphvizSetNodeColors(g, ["#FF0000", "#00FF00", "#0000FF"]);
+<graphviz graph xxx with 3 nodes and 0 edges>
+gap> AsString(g);
+"//dot\ngraph xxx {\n\t1 [color=\"#FF0000\", style=filled]\n\t2 [color=\"#00FF\
+00\", style=filled]\n\t3 [color=\"#0000FF\", style=filled]\n}\n"
+
 #
 gap> STOP_TEST("graphviz package: node.tst", 0);
diff --git a/tst/subgraph.tst b/tst/subgraph.tst
index 94d0bc3..5f16259 100644
--- a/tst/subgraph.tst
+++ b/tst/subgraph.tst
@@ -380,5 +380,41 @@ gap> o := GraphvizFindGraph(g, 1);
 gap> IsIdenticalObj(o, s);
 true
 
+# Test edge and node numbers when subgraphs are present
+gap> g := GraphvizGraph("main");;
+gap> a := GraphvizAddSubgraph(g, 1);;
+gap> b := GraphvizAddSubgraph(g, 2);;
+gap> c := GraphvizAddSubgraph(a, 3);;  # nested subgraph
+gap> GraphvizAddNode(g, 1);;
+gap> GraphvizAddNode(a, 2);;
+gap> GraphvizAddNode(a, 3);;
+gap> GraphvizAddNode(b, 4);;
+gap> GraphvizAddNode(b, 5);;
+gap> GraphvizAddNode(b, 6);;
+gap> GraphvizAddNode(c, 7);;
+gap> GraphvizAddNode(c, 8);;
+gap> GraphvizAddNode(c, 9);;
+gap> GraphvizAddNode(c, 10);;
+gap> g;
+<graphviz graph main with 10 nodes and 0 edges>
+gap> GraphvizAddEdge(g, 1, 2);;
+gap> GraphvizAddEdge(a, 2, 3);;
+gap> GraphvizAddEdge(a, 3, 4);;
+gap> GraphvizAddEdge(b, 4, 5);;
+gap> GraphvizAddEdge(b, 5, 6);;
+gap> GraphvizAddEdge(b, 6, 7);;
+gap> GraphvizAddEdge(c, 7, 8);;
+gap> GraphvizAddEdge(c, 8, 9);;
+gap> GraphvizAddEdge(c, 9, 10);;
+gap> GraphvizAddEdge(c, 10, 1);;
+gap> g;
+<graphviz graph main with 10 nodes and 10 edges>
+gap> a;
+<graphviz graph 1 with 6 nodes and 6 edges>
+gap> b;
+<graphviz graph 2 with 3 nodes and 3 edges>
+gap> c;
+<graphviz graph 3 with 4 nodes and 4 edges>
+
 #
 gap> STOP_TEST("graphviz package: subgraph.tst", 0);