Added comments

src/slic3r/GUI/GUI_ObjectList.cpp

@@ -270,6 +270,11 @@ void ObjectList::set_tooltip_for_item(const wxPoint& pt)
     HitTest(pt, item, col);
     if (!item) return;
 
+    /* GetMainWindow() return window, associated with wxDataViewCtrl.
+     * And for this window we should to set tooltips.
+     * Just this->SetToolTip(tooltip) => has no effect.
+     */
+
     if (col->GetTitle() == " " && GetSelectedItemsCount()<2)
         GetMainWindow()->SetToolTip(_(L("Right button click the icon to change the object settings")));
     else if (col->GetTitle() == _("Name"))

src/slic3r/GUI/GUI_ObjectManipulation.hpp

@@ -2,7 +2,7 @@
 #define slic3r_GUI_ObjectManipulation_hpp_
 
 #include <memory>
-#include <wx/string.h>
+#include <wx/wx.h>
 
 #include "GUI_ObjectSettings.hpp"
 #include "GLCanvas3D.hpp"