Method OnChangeButtonClicked

src/RealtimeEffectPanel.cpp:650–698

      }

      void OnChangeButtonClicked(wxCommandEvent& event)
      {
         if(!mDelegate || mProject == nullptr)
            return;

         if(mEffectState == nullptr)
            return;//not initialized

         const auto effectID = EffectsMenuHelper::PickEffect(
            *mProject,
            mChangeButton,
            mEffectState->GetID()
         );
         if(!effectID)
            return;//nothing

         if(effectID->empty())
            RemoveFromList();
         else
         {
            auto &project = *mProject;
            auto &em = RealtimeEffectManager::Get(project);
            auto oIndex = em.FindState(mDelegate->GetChannelGroup(), mEffectState);
            if (!oIndex)
               return;

            auto oldName = GetEffectName(*mEffectState);

            if (auto state = AudioIO::Get()
               ->ReplaceState(project, mDelegate->GetChannelGroup(), *oIndex, *effectID)
            ){
               // Message subscription took care of updating the button text
               // and destroyed `this`!
               auto effect = state->GetEffect();
               assert(effect); // postcondition of ReplaceState
               ProjectHistory::Get(project).PushState(
                  /*i18n-hint: undo history,
                   first and second parameters - realtime effect names
                   */
                  XO("Replaced %s with %s")
                     .Format(oldName, effect->GetName()),
                  /*! i18n-hint: undo history record
                   first parameter - realtime effect name */
                  XO("Replace %s").Format(oldName));

                  ToggleUi(project, *state, mDelegate->GetSourceName());
            }
         }
      }

      void OnPaint(wxPaintEvent&)
      {