Keep non-interactive effects from going into a recursive loop.

src/effects/Fade.h

@@ -38,6 +38,10 @@ class EffectFadeIn: public EffectSimpleMono {
       return wxString(_("Fading In"));
    }
 
+   virtual bool PromptUser() {
+      return true;
+   }
+
  protected:
    sampleCount mSample;
    sampleCount mLen;
@@ -68,6 +72,10 @@ class EffectFadeOut:public EffectSimpleMono {
       return wxString(_("Fading Out"));
    }
 
+   virtual bool PromptUser() {
+      return true;
+   }
+
  protected:
    sampleCount mSample;
    sampleCount mLen;

src/effects/Invert.h

@@ -41,6 +41,10 @@ class EffectInvert:public EffectSimpleMono {
       return wxString(_("Inverting"));
    }
 
+   virtual bool PromptUser() {
+      return true;
+   }
+
  protected:
    virtual bool ProcessSimpleMono(float *buffer, sampleCount len);
 };

src/effects/Reverse.h

@@ -44,6 +44,10 @@ class EffectReverse:public Effect {
       return wxString(_("Reversing"));
    }
 
+   virtual bool PromptUser() {
+      return true;
+   }
+
    virtual bool Process();
 
  private: