Fix of a regression update issue of the "modified" flag

at the active profile, specific to OSX.
https://github.com/prusa3d/Slic3r/issues/632

xs/src/slic3r/GUI/Preset.cpp

@@ -519,6 +519,11 @@ bool PresetCollection::update_dirty_ui(wxBitmapComboBox *ui)
 				ui->SetString(ui_id, wxString::FromUTF8(new_label.c_str()));
 		}
     }
+#ifdef __APPLE__
+    // wxWidgets on OSX do not upload the text of the combo box line automatically.
+    // Force it to update by re-selecting.
+    ui->SetSelection(ui->GetSelection());
+#endif /* __APPLE __ */
     return was_dirty != is_dirty;
 }