Build customization "{0}" uses file extension "{1}". This file extension is currently mapped to {2} "{3}" in one or more ...

Build customization "{0}" uses file extension "{1}".  This file extension is currently mapped to {2} "{3}" in one or more project configurations for project "{4}".

Files with this extension (that do not have file-level properties set) may use this build customization instead.  Do you still want to save the changes?