Gui: use empty

src/Gui/Placement.cpp

@@ -371,7 +371,7 @@ void Placement::on_selectedVertex_clicked()
     Base::Vector3d firstSelected; //first selected will be central point when 3 points picked
     for (std::vector<Gui::SelectionObject>::iterator it=selection.begin(); it!=selection.end(); ++it){
         std::vector<Base::Vector3d> points = it->getPickedPoints();
-        if (it==selection.begin() && points.size()>0){
+        if (it==selection.begin() && !points.empty()){
             firstSelected=points[0];
         }
         picked.insert(picked.begin(),points.begin(),points.end());