rm unused ret value

GUI/Model/Sample/ParticleItem.cpp

@@ -58,9 +58,9 @@ std::unique_ptr<Particle> ParticleItem::createParticle() const
     return particle;
 }
 
-SessionItem* ParticleItem::setFormFactor(const QString& model_type)
+void ParticleItem::setFormFactor(const QString& model_type)
 {
-    return setGroupProperty(P_FORM_FACTOR, model_type);
+    setGroupProperty(P_FORM_FACTOR, model_type);
 }
 
 bool ParticleItem::isFormFactorPropertyName(const QString& name)

GUI/Model/Sample/ParticleItem.h

@@ -35,7 +35,7 @@ public:
     std::unique_ptr<Particle> createParticle() const;
 
     template <typename T> T* setFormFactorType();
-    SessionItem* setFormFactor(const QString& model_type);
+    void setFormFactor(const QString& model_type);
     static bool isFormFactorPropertyName(const QString& name);
     FormFactorItem* formFactor() const;
     GroupItem* formFactorItem() const;