How to create submenus (or multiple command UIs)

I have some UI

Everything into the Command UI is a Imgui::Button inside the callback

    ImGui::InputInt("Radius", &radius);

    ImGui::SameLine();

    //
    // Button
    if (ImGui::Button("Max Curvature"))
    {
        // get mesh
        polyscope::registerSurfaceMesh("mesh", V, F);
        
        // Compute curvature directions via quadric fitting
        MatrixXd PD1, PD2;
        VectorXd PV1, PV2;
        std::vector<Index> bv = {};
        
        igl::principal_curvature(V, F, PD1, PD2, PV1, PV2, bv, radius);
        
        polyscope::getSurfaceMesh("mesh")
            ->addVertexScalarQuantity("Max Curvature", PV1,
                                      polyscope::DataType::SYMMETRIC);
        
    }

pretty standard. Now I'd like to add the "radius" input inside the button scope, so that when I press the button all the relevant data is presented to the user.
Of course, if I simply put the input widget code inside the button one the input widget is just show for an instant then deleted, as the callback runs over and over.
The best option would be to create a separate sub-UI, possibly opening down below the command UI itself. Or to create multiple command UIs.
Is there a way?
Thank you

Inizia con il callback di Command UI e l’uso di ImGui::InputInt e ImGui::Button mostrato nell’issue. Determina come un input del raggio persistente o un sottomenu separato potrebbe rimanere visibile tra le invocazioni del callback e definisci quale interazione debba essere considerata completata; l’issue non indica file né test.