select_next_item() work only with history selection? I'm trying to use select_next_item() function to select the next vertex , and I select the vertices from a List . 

Unfortunately it does not work

Here is simple code:

import bpy,bmesh


obj = bpy.context.object.data

bm = bmesh.from_edit_mesh(obj)

vert = []

for v in bm.verts:
    if v.select:
        vert.append(v)

bpy.ops.mesh.select_all(action='TOGGLE')

vert[0].select=True
vert[1].select=True        

bpy.ops.mesh.select_next_item()

bmesh.update_edit_mesh(obj)


Thanks in advance.
Using vert[0].select=True doesn't add the vertex to the bmesh select history, you need to add it yourself.

vert[0].select=True
bm.select_history.add(vert[0])
vert[1].select=True        
bm.select_history.add(vert[1])


You may notice that the select history doesn't include all selected items, if you Alt-Click to select an edge loop only one vertex (the active vertex which was closest to the click) is added to the history. Shift-Alt-Click will then add a second vertex which is the new active vertex. If you use select all then nothing is in the history.