The popup menu in ctkTreeComboBoxTest1 was not closed

It's because at the time the popup is asked to be closed, the popup is not
even visible (because of the scroll animation), disable the animation in
the example.

Libs/Widgets/Testing/Cpp/ctkTreeComboBoxTest1.cpp

@@ -51,9 +51,13 @@ int ctkTreeComboBoxTest1(int argc, char * argv [] )
     return EXIT_FAILURE;
     }
   combo.show();
-  
+  // if the effect UI_AnimateCombo is enabled, the popup doesn't have time
+  // to be visible when hidePopup() is called wich doesn't hide the popup.
+  bool oldEnabled = QApplication::isEffectEnabled(Qt::UI_AnimateCombo);
+  QApplication::setEffectEnabled(Qt::UI_AnimateCombo, false);
   combo.showPopup();
   combo.hidePopup();
+  QApplication::setEffectEnabled(Qt::UI_AnimateCombo, oldEnabled);
   
   if (argc < 2 || QString(argv[1]) != "-I" )
     {