FIX: [STUDIO-3217] hide dropdown when combobox move by scroll

Change-Id: I8d8e9ec4a54f6418843463f1bf4f1f46fd4af3df

src/slic3r/GUI/Widgets/ComboBox.hpp

@@ -88,6 +88,7 @@ private:
     void mouseDown(wxMouseEvent &event);
     void mouseWheelMoved(wxMouseEvent &event);
     void keyDown(wxKeyEvent &event);
+    void onMove(wxMoveEvent &event);
 
     DECLARE_EVENT_TABLE()
 };