Combined mode in this mockup is not different than Vertex Select Mode.
How a user is supposed to understand that he is in a combined mode Vertex+ Edges and not in Vertex+Faces or Vertex+Edges+Faces ?
Since fusion of unwrap and edit mode, unwrap tools are using the idea of an active Face.
You can be in Vertex Select mode or Edge Select mode and unwrap your mesh.
There are both kinds of active element : an active vertex or an active edge and an active face.
Although follow active quads operator is restricted to activation of face select mode.
Mock-up is neglecting a solution for Edges+Faces combined mode.