I am trying to create a graph which allow the user to create new vertices and edges. clicking on an empty spot in the graph creates a new vertex, and clicking an existing vertex creates a popup window which allows adding edges from it. this is some minimal code for example (sorry, it's still a bit long):

radioMarkedVertexFunction[Hold[g_Symbol]] := 

Function[{pos, name, dim}, {
    Disk[pos, EuclideanDistance[{0, 0}, dim]],
      PopupMenu[Dynamic[edgeAdd$dst], VertexList[g]],
      Button["New Edge", If[MemberQ[VertexList[g], name],
        g = EdgeAdd[g, name \[DirectedEdge] edgeAdd$dst]]
    WindowTitle -> Dynamic[name]
  Dynamic[graph], {
   "MouseClicked" :> (graph = Block[{
        pos = MousePosition["Graphics"],
       If[FreeQ[pos, None],
        near = Nearest[GraphEmbedding[graph], pos][[1]];
        Print["pos:", pos, " nearest:", near, " \nout of: ", 
         Nearest[GraphEmbedding[graph], pos]];
         EuclideanDistance[pos, near] > 0.1,
         VertexAdd[graph, Unique[]],
     ), Method -> "Queued" (*should help for bigger graphs*)
 Initialization :> (graph = Graph[
     {1 -> 3},
     VertexLabels -> "Name",
     PerformanceGoal -> "Quality",
     VertexShapeFunction -> radioMarkedVertexFunction[Hold[graph]]

The functionality described above is working fine, but I have a wierd problem, I used the option:

WindowTitle -> Dynamic[name]

so that every popup window will bear the name of its relevant vertex (s.t. if you create a new edge, you will now where it starts.) the title is fine for nodes created by clicking, e.g.

A popup with the vertex's unique name as title

in contrast to

A popup with $Failed as title

so what's up with that? all popups get their title as an argument to the vertex shape function, so why are some not evaluated?

Thanks in advance!


1 Answer 1


It fails because WindowTitle can't handle e.g. Integers but it can e.g. Symbols or Strings. Which is even more than I thought because I was expecting that only strings work.

ref/WindowTitle/PossibleIssues says:

WindowTitle should be set to something that formats as a simple string of text

Which is not very precise but it is something.

Nevertheless, you can format it properly using e.g.:

WindowTitle -> Dynamic[ToString[name, InputForm]]
  • $\begingroup$ wow, that was much simpler than I suspected. thanks! $\endgroup$
    – Nailo
    Oct 11, 2017 at 14:17

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