3ds: move ui7 to bottom screne

tests/gfx/include/os-ctx.hpp

@@ -21,6 +21,8 @@ class OsCtx {
   virtual bool Mainloop() { return false; }
   virtual void ClearViewPort() {}
   virtual void SwapBuffers() {}
+  virtual int GetScreenCount() { return 1; }
+  virtual void DrawOnScreen(int s = 0) {}
   PD::fvec2 PositionTranslate(PD::fvec2 in) {
     return fvec2(in.x * pViewPort.x, in.y * pViewPort.y);
   }

tests/gfx/include/os/horizon-ctr.hpp

@@ -13,6 +13,8 @@ class HorizonCtr : public PD::OsCtx {
   bool Mainloop() override;
   void ClearViewPort() override;
   void SwapBuffers() override;
+  int GetScreenCount() override { return 2; }
+  void DrawOnScreen(int s) override;
 
  private:
   struct Impl;