fixed small bug in the ui

Former-commit-id: 071d7a9dbfe99b420f0de75899e24dcd8fdf7127

include/igl/opengl/glfw/imgui/ImGuiMenu.cpp

@@ -221,7 +221,7 @@ IGL_INLINE void ImGuiMenu::draw_viewer_menu()
     ImGui::DragFloat("Zoom", &(viewer->core.camera_zoom), 0.05f, 0.1f, 20.0f);
 
     // Select rotation type
-    static int rotation_type = static_cast<int>(viewer->core.rotation_type);
+    int rotation_type = static_cast<int>(viewer->core.rotation_type);
     static Eigen::Quaternionf trackball_angle = Eigen::Quaternionf::Identity();
     static bool orthographic = true;
     if (ImGui::Combo("Camera Type", &rotation_type, "Trackball\0Two Axes\0002D Mode\0\0"))