[Closed] scripted modifier plugin, building upon existing modifiers

Hi,

I want my modifier to be able to work on vertex and edge modes. So I’ve decided to build it upon Mesh_Select. This is a piece of code that pretty does nothing, but:

plugin modifier CrispEdges
	name:"Crisp Edges"
	classID:#(1418230114, 912667686)
	extends:Mesh_Select
	replaceUI:false
	version: 0.01
(
  parameters main rollout:params
  (

  )
  rollout params "Parameters"
  (
    spinner seglen "Seg Length: " range:[0.01,1e9,20]
  )
)

Manually I can get into subObjectLevels 1,2,3,4,5 (goind to vertex mode, the listener returns subobjectLevel = 1 ) but I can’t do it by maxscript (I get an error: Requested sub-object level out of range). numSubObjectLevels returns 0 (?).

Is it a good way to build upon existing modifiers? Actually all I want is just be able to select vertices and edges.